One afternoon Tom offered to sell his drum kit to Sarah for $300. That night Sarah wrote Tom a letter stating she accepted the offer and would buy the drums for $300 and she placed it in the mail. The next day Tom saw Sarah and told her that he was withdrawing his offer and wanted to keep the drums. Two days later, Sarah's letter was received by Tom. Which of the following statements is true?

Question 13 options:

a) Tom's offer was revoked.

b) Tom's offer was effectively accepted by Sarah.

c) Sarah's letter constituted a counter-offer.

d) none of the above.