B, and it seems like a mind-bogglingly obvious choice (though I would want to see a demonstration of the computer first, and put in some safeguards to prevent burning through too much of m computation at any given time (i.e. only allow it 10^^(10^^10-1) operations for any instruction I give it to keep an infinite loop from making it worthless). My choice wouldn't differ, even if I didn't have function f, because that's basically a "map the genome, simulate cells directly from physics (and thus solve the protein folding problem), solve any problem where the limit is computation, and generally eliminate all suffering and solve every human problem" machine. If I wanted to, I could also run every turing machine with 10^10 or fewer states for 10^^(10^^10-1) cycles, though I'm not sure whether I'd want to.

We expect people to lay down their lives immediately to save even 10 others. Why wouldn't we do so to save literally every other human on the planet and give them basically unlimited life?