Jack arches a brow but figures, again, if he's trusting this is the real Carter (or one of them - there's a lot of realities out there and he doesn't know which one he's in) he needs to be honest with her.

"I went to Atlantis for a joint Homeworld Security and IOA evaluation of the Lantean transition...thing. Anyway, turns out they were Replicators and I ended up stuck with Woolsey's ass and half-drowned. And then here."