All of these could be considered an "author's purpose". An author is technically anyone who writes anything, therefore the purpose of writing is theoretically limitless. If you have to choose one of these, however, it would be "to remind".
Answer:
Posiedon claims Percy as his child or Percy heals using water during the capture the flag fight?
Act 2, Scene 3- Friar Lawrence compares Mother Nature “womb and tomb” to earth
The answer would the second choice B