You should answer this in your own words or it could be considered plagiarism and may make you fail the question or worse, the test.
The prepositional phrase is "After the rain"
Answer:
First of all, I LOVE PERCY JACKSON! Enjoy reading!
Second of all, I think sending Medusa's head was a good idea. By doing this, Percy reminded his dad that he's still here, and he's kind of angry for him only claiming him to go off on a quest to clear Poseidon's name.