Yep evaporative cooling is an adaption. Though if it goes for too long it will die. The question implies an unusually hot day so this response wouldn't kill them plant in this case..
Also its worth noting that option A is correct, but not a completely distinguishing factor since viruses are also non-cellular. A difficult question, easy to make a mistake in a multiple choice form!
I think this is a case of the 'most correct'. Yes DNA isn't in prions, but equally there is no RNA therefore the 'no nucleic acid' response is the 'most correct' even though both are correct.
Dux has got anywhere from 97-99 over the past few years. I've done a few past papers and they're probably at a similar level to school papers (some a little easier, some a little harder)...