A proposal, when accepted, becomes a/an

Option (1) is correct: When the person to whom the proposal is made, signifies his assent thereto, the proposal is said to be accepted. A proposal, when accepted, becomes a promise. Option (2) is incorrect: Every promise as well as every set of promises, forming the consideration for each other, is an agreement. Option (3) is incorrect: An agreement enforceable by law is a contract. Option (4) is incorrect: A consideration is something of value given by both the parties to a contract that induces them to enter into the agreement to exchange mutual performances.