Adam, age 16, recently lost his parents in an automobile accident. Adam moved into the home of his aunt and uncle, but he has a job, is able to support himself financially, and pays rent to his aunt and uncle. Adam purchased a motorcycle from Sam Seller for cash payment of $5,000, the market price, and Adam registered the motorcycle in his name with the Department of Motor Vehicles. After keeping the motorcycle for 3 months and driving it for 2,500 miles, Adam decided he wanted to return it to Sam and get his money back so that he could buy a car instead. Which of the following best supports Sam's argument that the contract is binding on Adam?

a. Adam cannot disaffirm the contract because the motorcycle has suffered from depreciation through its use.

b. The motorcycle would be a necessary since he uses it to get to work and support himself financially.

c. The contract is enforceable because the price was fair and there is no evidence that the motorcycle is defective.

d. The contract is enforceable because it has been fully performed by both Adam and Sam for a substantial period of time.