Which of the Following Statements Would Make the Best Closing

Multiple Choice

Which of the following statements would make the best closing for the message?

A) Thanks so much-you're the best!
B) Get back to me ASAP if you will participate.
C) Thanks to all for considering helping-interested parties should email me at the address below by Friday.
D) We are very grateful to those people who will actually make the time to help us out. Let me know if you are interested.
E) Submit the attached form within a week if you are able to participate.