2 or 3 is the answer. My thinking, 2 originals + the pronoun 'you', a terribly vague implied referent. If scifi and 'you' means the 'alien' (not a people) then 2 is the answer, but if 'you' means me, the reader, (one of the people) then 3 is correct, unless some of your readers are aliens, and then it would be vague again.