S, a manufacturer of kitchen equipment for restaurants, wrote to B: "September 1, I offer to sell you one mixer industrial strength, price $2,000. This is a firm offer for one month until October 1. [Signed] S. Your acceptance must be received at my office by October 1." The letter was received on September 2.

On September 10, B received a letter from S: "I hereby revoke my offer of September 1."

On September 17, B wrote to S: "I hereby accept your offer of September 1." The letter was mailed on September 17 by authorized means but was lost in the mail and never received by S.

A. Is a contract formed? Explain.

B. Instead of the facts stated in (a) assume that S's offer stated that it was a firm offer for four months, and that on October 10, B mailed an acceptance that was received on October 12. Is there a contract? Explain.

C. Instead of the facts stated in (a) assume that S's offer stated that it was a firm offer for four months, and that on December 14, B received a letter from S, dated December 12 which stated: "I hereby revoke my offer of September 1." On December 15, B mailed an acceptance that was received on December 17. Is there a contract? Explain.