What is the term for what the promisor requires as the price for a promise?

The term that defines what the promisor requires as the price for a promise is "consideration." In legal and contractual contexts, consideration refers to something of value that is exchanged between parties entering into a contract. It can be a benefit to one party or a detriment to another, but it must be something that the parties have agreed upon as part of their deal. Without consideration, a promise typically lacks enforceability because there is no exchange or mutual benefit involved.

This concept is foundational in contract law; it ensures that both parties are providing something of value, thus establishing a legal binding agreement. Consideration distinguishes legally enforceable agreements from mere promises that are not backed by an exchange, which is essential for the validity of a contract.

The other options do not accurately describe this pricing mechanism: "obligation" generally refers to a duty or commitment that one party has to another, while "compensation" is often associated with payment for services rendered or loss incurred, and "contractual agreement" is the overarching term for the whole contract, not just the price component.