Answer:
enforceable because it has been expressly ratified by Melissa.
Explanation:
A contract is defined as a legally binding agreement between parties, and is enforceable on both parties involved. There is usually an offer and acceptance to make the contract valid and enforceable. It can involve exchange of goods and services, or future promise to exchange goods and services.
In this instance bMelinda agreed with Umberto that she will buy a car from him when she turns 18 years. The condition to the contract was Melinda turning 18 years.
She has ratified this condition so the contract is now enforceable.