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12. Ma Rainey made the following offer to Levee: "I will pay you $500 if you agree to play trumpet on my next recording." Levee replied that he promised to play trumpet on Ma's next recording. At this point, the contract is an (A) executed, bilateral, express contract; (B) executory, bilateral, implied-in- law contract; (C) executed, unilateral, express contract; (D) executory, bilateral, express contract. Answer: Explanation