Jean says to Joan, "If you'll promise to feed my dog each day while I am out of town next week, I'll pay you $100." Joan replies, "I'll absolutely do that. I hope you have a nice trip." Joan then feeds the dog, after which Jean pays her. At what point did a contract come into existence?
(A) When Jean made the offer to Joan.
(B) When Joan said that she would feed Jean's dog.
(C) When Joan started feeding Jean s dog.
(D) When Joan completed the final feeding of Jean's dog,
(E) When Jean paid the $100 to Joan.