Kathleen Offers to Buy Richard's Prize Stallion for $10,000 Only

Kathleen offers to buy Richard's prize stallion for $10,000 only if a licensed veterinarian certifies that the horse is sound for breeding.After inspecting the stallion,the veterinarian concludes that the stallion is sterile and thus not fit for breeding.Kathleen

A) must still buy the stallion.
B) does not have to buy the stallion.
C) must still buy the stallion,but may pay a lower price.
D) does not have to buy the stallion,but must buy another horse of similar value from Richard.