Sarah Seller offers to sell Brianna Buyer her first year contracts book for $50, on the condition that Sarah's favorite singer, Angela Acapella, win "U.S.A. Icon," a popular singing competition. Brianna 20 accepts. Angela got knocked out of the competition early on. Brianna demands that Sarah still sell her the book, but Sarah refuses. Is Sarah contractually obligated to sell the book?
(A) Yes, because Sarah made an offer to sell the book and Brianna accepted the offer.
(B) Yes, because Sarah's condition was not related to the sale of the contracts book.
(C) No, because Angela did not win "U.S.A. Icon."
(D) No, because Sarah effectively revoked her offer.