Answer:
C. Thunder and lightning will ruin a pool party, so the weather really isn't "great."
Explanation:
Verbal irony, simply put, is saying one thing, but meaning another, usually completely opposite. It is closely associated with sarcasm and it is often used for humorous effect.
In this particular case, it is obvious that thunderstorm and pool party don't go together. The author is aware of this, so, by saying the weather is "great", when clearly it is not, he uses a verbal irony.
