There is no answer to that question. Even if K had one, he doesn't have the relationship with the dead that Jesus does; his answer won't have the context Jesus needs. He can't bring himself to ask it to Rosita, not after she already had to bury him. His death is a topic they've mutually agreed to box up and move past.

It's what he'll do now that he's said it to K, too.

He grasps K's hand. If he can't pack up the emotions and the steady, invasive fears he has now, he can at least accept some comfort.

"You still haven't eaten," he points out, but he doesn't let go.