A Minor, who is below the age of majority in the relevant jurisdiction, enters into a contract with Defendant (who is above the age of majority). The contract, which was not in writing - and did not concern real estate or collateral promises, provided that both parties provide valid consideration, and was for a lawful purpose. The payment term for the contract was $5,000, with Minor to make the payment within six months of the formation of the contract. After the contract was formed, Defendant changed his mind, and sought to terminate the contract. Minor threatened to sue should Defendant breach the contract, but Defendant breached anyway. Minor sues within the time established by the statute of limitations. Defendant prevails. On what basis?