Read the email below and answer the question. Subject: Birthday Party! Hi Tom, I'm organizing a birthday party for my sister, Lily, on Saturday, May 18th, at 3 PM. It will be at our house. We'll have cake, games, and lots of fun! Please let me know if you can make it by May 15th. Hope to see you there! Best, Sarah What is the main purpose of Sarah's email?
A) To invite Tom to a party.