20 years or suicide?

I would probably choose choice B

since I don't believe in anything like heaven, hell, or any other worlds after you die.
And after taking into account that everyone believes you are dead and you are faced with 20 years of isolationism with your knowledge limited to what you know.

If you think about it you are limited to knowledge you know at that time which means that although you can order things such as anime and manga you would be limited to what you knew existed
Also if you choose to study something like an instrument say the Tuba for example

You would have no idea on how to play it. All you see is a bunch of button like things on a long tube which at one end you blow through it. And remember since you are limited with only your current knowledge you would only to be able to get music and practice books that you no the name of.

For the people who think that one of the reasons to choose room A would be so that you could be awesome at __(insert game here) you have to think about what happens to the game in 20 years. Say you practiced Crysis or Bioshock so much that you became unbeatable. In 20 years no one might even care about those games so that would be pointless.

Also if you think about the clone and other than the fact that your going to fuck it ever hour or so you'll probably do everything you wanted to with it after the first two weeks.

And if you do manage to go through the 20 years resembling something of your old self you would be:
socially awkward,
(in all likliness if you are young) unrecognizable,
lacking in skills that you would require to make a living (using a modern computer),
lacking in information about world affairs, the state of the world, and technology,
without an identity (you have been dead for 20 years remember)
without currency
etc.

For the sake of those who have attempted to read and wish to get this post over with I will sum up what I want to say. Basically:
Room A is an option that means that from this point on you are going to live a living hell
Room B is an option to avoid that hell and end your life

For the sake of my desire to support my point further and for the sake of those who have nothing to do but read this I am going to continue this in the spoiler

WARNING THIS IS SOME SERIOUS SHIT THAT WILL REQUIRE YOU TO THINK TO UNDERSTAND

essentially you are an anachronism. Something comparable to taking a man who lived in 1930 (the great depression) and placing him in the year 1950 (the cold war). Or taking a tiny pebble and throwing it into a mountain of rocks.

I use the rocks as an example because compared to the mountain the pebble has little value.
The man similarily has little value as
(assuming he had to do the same thing and choose room A)
the value he had prior to the 20 years existed because he had NET worth and people who valued him.
Now with his identity gone (he has been officially dead for a while) he has no net worth (no belongings, money, etc.) and the people he knew believe he is dead so they don't require him or in other words he is no longer needed (and no longer valued much by them). Additionally much of his knowledge about technology will probably be obsolete.
(think about the two years, 1930 and 1950, and the differences in technology,
example: the jet engine and nuclear energy)
Now unless some benefactor who:
had fond memories of him wishes to revive his value,
or just wants to amuse themselves by doing something like this,
or wishes to add to their own value by adding to his
helps him he is essentially a beggar on the streets.

So choosing room A will just lead to a living hell because you will first go insane from being isolated and then lose all value because you are no longer needed in the lives of others which will make you feel like you are no longer needed and thus wanted. Additionally what do you really think people who are confronted by a person who is claiming to be someone from 20 years ago going to think.

And Room B is just a way to escape that hell and end your life which no longer equates to much anyways.

After grabbing the gun, I would then bust the guard with a bullet, taking his gun. After throat punching two more guards, I jump into the air vents, crawling MGS style, and exiting into the control room, where I release several other prisoners for a diversion. Quickly, I make my way down the hall, weaving through the chaos created by men and women locked up for years, sirens going off, lights flashing a morbid red color. I find, the room I am looking for: cell B-1.
I look through the small glass in the door, seeing a woman laying on the floor. I kick the door open, and grab my long lost lover. She turns her eyes up to me, her face is suken in, the life gone from her smile. She can't recognize me, she only smiles a ghostly smile. "It's me... baby... it's me... I've come to get you out... don't you recognize me...?"
My backup arrives, Hale enters the room, breathing heavily. "We have to go - NOW". The tears wellup in my eyes, I turn to my friend, at a loss for words. She's gone... her body is here, but her mind, her spirit, her very soul is gone... I shout to her one more time, "Honey, answer me! I'm here! It's me!" I know it's usless, they've experimented on her to long. She's just a husk, nothing of the girl I once loved remains.
My hands are trembling, the muscles in my face tighten, "I don't know what to do man... Hale... she just... she's not...", the words just don't come out. I know what I have to do, but I can't find it in me to do it.
A gentle hand grabs my shoulder, I look up to see Hale with compassion in his eyes. "It's okay man... it's okay... but you have to let her go... you'll see her again one day... but right now we have to go..."
I can't hold back the tears, my sobs echo throughout the cell, throughout the hallway, and thoughout my mind. I raise my pistol towards her, and say a final I love you...
A shot rings out... my body jumps, the woman in my arms goes limp...
Ten minutes later another shot rings, a man with a twisted smile sitting in a chair surrounded by monitors of cells filled with inmates, slumps forward. Blood pours from his head. He never had a monologue, no final words, no explainations, I didn't want to hear them...
Three minutes later the compound explodes, and I watch from above in a helicopter stamped with FAKKU! on the side. The pilot gives us a thumbs up, congratulations go around, someone passes around cigars. I take a picture out of my wallet, it's of a couple holding a baby that never made it to age 1, a women who was kidnapped from her home, a man who'd never see them again. On the back it is inscribed, "To my love, whom I will be with..."
I pull out my pistol, place a single bullet inside and began to raise it to my head. Thoughts of what could of been flash in my head, smiling faces, children's laughter, a women's touch, a mother holding a baby...
Hale's voice shouts out over the sound of the helicopter blades, "She really loved you, you know? Thats why she never told them where our base was, she wanted to protect us - protect you...".
I put the gun down, unload the chamber. She protected me from myself... if only I could of protected her...