"Um," First Aid says, because it's either that or say, 'what the fuck?' out loud, and that would be very unprofessional.

"You said you used to run on a plasma reactor?" is the next thing he says, mostly to buy time to think. That is not, definitely not a plasma reactor.

"How long have you been on the island, exactly?" is the third thing, for the purpose of data collection and calculating damage rates.