In a face-to-face conversation, non-merchant Seller offers to sell his old smart phone for $100 to non-merchant Buyer. Buyer replies: "I'll pay you $75 for it." Seller says: "I cannot reduce the price, but my offer remains open to you until tomorrow." The next day Buyer tells Seller: "OK, I'll pay $100 for the phone." Are Buyer and Seller in an enforceable contract?
(A) Yes, because Seller said the offer remained open.
(B) Yes, because Seller made an irrevocable firm offer when he said the offer remained open.
(C) No, because Buyer made a counteroffer and the power of acceptance was terminated.
(D) No, because in a face-to-face conversation, the power of acceptance terminates when the conversation ends.