In All but One of the Following Situations, the Contract

In all but one of the following situations, the contract is frustrated. Identify the exception.

A) Wacky had contracted to supply a health-food store jars of melatonin, a hormone now thought to be a miracle potion. After the contract but before the delivery, the government banned the sale of melatonin so that it could be properly tested under government auspices.
B) Craig, a trucker with whom you contracted last month to transport stoves tomorrow, phones to tell you that his truck has broken down.
C) Tracey contracted to sing at a local club on March 10, but that morning the club was destroyed by lightning.
D) On December 1, Pak contracted to buy Scott's horse, to be delivered day December 10. On December 8, the horse contracted rabies and had to be destroyed.
E) You agree to paint Joe's house on the following Tuesday, but on the Monday before, through no fault of either party, the house is destroyed by fire.