Okay, tough question here!

You're abducted by aliens, and they show you their weapon - it's so powerful that it can destroy Earth in one millisecond. Then they tell you that they're going to experiment on you for the rest of your life, which includes exposing you to different alien viruses and plants and creatures. During breaks in the tests, you'd get a nice place to sleep, human food and clean water, and lots of books. At any time, if you don't want to be tested on anymore, you will be allowed to press a button which automatically kills you. However, you can opt out of being experimented on, and still live - the aliens will shoot their weapon and annihilate Earth and everyone on it. You'll still live life on their ship, with food, books, and water, just no being experimented on, and plus you can choose one Earthling to save (who will live with you on the aliens' ship). What do you do? Do you sacrifice yourself and be experimented on so Earthlings can live? Do you press the suicide button? Or do you have all but one Earthling survive, and spend the rest of your life with them on the ship?