Rea Says "Susan, I Will Sell You My Car for $5,000

Rea says "Susan, I will sell you my car for $5,000." Susan says, "I'll give you $4,500." Rea says "No." Later Susan calls Rea and says, "I have $5,000 and want the car." Rea:

A) must sell the car for $5,000, since the offer was accepted
B) must sell the car for $5,000 since the offer was accepted in a timely fashion
C) does not have to sell the car because there never was a firm offer by her to sell
D) does not have to sell the car to Susan because her offer was not accepted quickly enough
E) none of the other choices