Mary Bought a New Macintosh Computer and Advertised Her Old

Mary bought a new Macintosh computer and advertised her old computer system for $1,500. Mr. Jones offered to pay $1,000. Mary said no, she wanted $1,500. Mr. Jones offered $1,250. Mary rejected that and said she wanted $1,500, but then said to him, "I withdraw my offer, I've decided to give it to school and apply for the tax benefit." Mr. Jones said, "All right, I'll accept your offer of $1,500." Which of the following is true?

A) There is a contract because at some point in time Mary was willing to sell and Mr. Jones was willing to buy the computer system for $1,500.
B) There is a contract, because once a seller makes an offer she cannot change her mind; she is bound to receive an acceptance.
C) There is a contract and Mr. Jones has to pay a reasonable price for Mary's old computer.
D) There is no contract because the last offer had lapsed.
E) There is no contract because Mary revoked the offer before Mr. Jones attempted to accept it.