On May 1, A makes a written offer to B for the sale of A's car. On May 2, A mails B a letter revoking the offer. On May 3, A telephones B to tell him that he is revoking the offer. On May 4, B learns that A has sold the car to C. On May 5, A's letter finally gets to B. A's offer terminated on:
A. May 2.
B. May 3.
C. May 4.
D. May 5.