Carlos Visited Vancouver Last Summer and Instead of Going Back

Carlos visited Vancouver last summer and instead of going back to Ontario he stayed and enrolled at Simon Fraser University. He needed money but didn't need things left in Ontario, including his car. In mid-December, he wrote a friend and offered to sell the car for $4,000 and told him to send him a letter with his answer. His friend received the letter on January 2, checked his financial situation, and sent a letter of acceptance January 3. Meanwhile Carlos, short of cash and not hearing from his friend, sold the car to Mr. Reno on December 31. Carlos received his friend's letter January 8. On these facts, which of the following is true?

A) The acceptance was effective before it was received, so there was a contract between Carlos and his friend.
B) All methods of acceptance are effective upon receipt by the offeror.
C) Sending an acceptance by mail was not a reasonable method of acceptance in this situation.
D) The letter of acceptance was effective when it was received, and by then Carlos had sold the car, so there was no contract.
E) In order for there to be a binding contract, there must be an offer and receipt of the letter.