C. to <span>persuade the reader that by taking steps now they can help fight the damage done to earth's atmosphere.</span>
Macbeth goes to see the witches again because everything they have told him has been true, so going to see the witches again will help determine whether Fleance is a threat to his throne.
Things that have been true that he was told:
He became the Thane of Cawdor.
Then became the King of Scotland.