Colby contracts in writing to sell his 2005 Dodge-brand pick-up truck to Efrem for $10,500. Colby agrees to deliver the truck on Friday, and Efrem promises to pay the $10,500 on the following Monday. On Thursday, Efrem tells Colby that he changed his mind and will not buy the truck. Over the weekend, Efrem changes his mind again and tenders $10,500 to Colby on Monday. Colby has not sold the truck to another party but refuses the tender and refuses to deliver. Efrem claims that Colby has breached their contract. Colby contends that Efrem’s repudiation released him from his duty to perform under the contract. Who is correct, and why?