On Monday, Abner offers to sell his trained golden retriever, Track, to Bob for $300 cash. “My offer is open until we go hunting next Saturday.” On Tuesday, Carl offers Abner $400 for Track, in eight equal monthly payments of $50. Abner says “Sorry, my price is $300 cash.” On Wednesday, Dan learns that Abner has offered to sell Track. Dan tells Abner, “I’ll pay $300 cash when you deliver the dog at the end of this year’s duck hunting season. But you can keep Track until then.” Abner says, “Sounds like a good deal. Okay, you now own Track.” He phones Bob and tells him of the sale. On Thursday, Carl phones Abner and says, “I accept your offer. I’ll pay $300 cash. When can I pick up Track?” Abner replies, “Sorry, but Track’s been sold.” Has Abner breached a contract with Bob or Carl? Has he been ethical in his conduct?