Concept:A legally binding agreement between two parties is called a contract.Explanation:Not every agreement is enforceable by law.When two people make an agreement that the law recognises and enforces, it becomes a contract.The law gives such an agreement legal effect, meaning the parties must fulfil their promises.Consideration is the value exchanged, an offer is a proposal, and agreement is the general meeting of minds.Only a contract has the force of law behind it.Answer:C. contract