Answer:
C. Situational
Explanation:
Since you've studied, thinking it wasn't going to be open book/note, you didn't need to study as hard and feel like it went to waste. So in this case, the irony is situational.
I think the answer is When a solar flare erupts, it has the force of a hundred million hydrogen bombs. This is the answer because a bomb is dangerous and a solar flare is probably a type of fire thing cause by the sun so that makes the most sense and provides an example of a violent type of space weather.
