Mrs Livingstone Puts an Ad in the Times Offering $5000

Mrs. Livingstone puts an ad in the Times offering $5000 to anyone who finds out what happened to her husband, David, who left on safari in Africa. Stanley fits himself out to find Livingstone, notifies Mrs. L of his intentions, goes to Africa and begins tracing David's trail. Mrs. L decides she likes life as a single woman, and puts an ad in the Times revoking her offer.

A) Mrs. L can revoke the offer because there has been no acceptance.
B) Mrs. L cannot revoke the offer because Stanley has accepted it.
C) Mrs. L cannot revoke the offer because Stanley has partially performed, creating an implied option.
D) Mrs. L can revoke, but only if she succeeds in getting notice to Stanley in the African jungle.
E) none of these