What best describes an opinion contract?

An opinion contract specifically refers to a situation where one party expresses a personal view or belief, and this expression does not create a binding obligation. The term "lack of consideration" highlights that, in legal terms, consideration is a necessary element in a contract to make it enforceable. If an opinion contract lacks mutual consideration—meaning there is no reciprocal exchange of value between the parties—then it cannot be legally enforced. This reinforces the idea that simply sharing an opinion or making a promise, without an exchange of value, does not result in a legally binding contract.

Examining the other options provides further clarification: a promise made with mutual consideration would actually constitute a valid contract with enforceable obligations, while a formal agreement with specific terms would imply clarity and definition that an opinion contract does not possess. Similarly, requiring written consent from all parties would denote a more formalized contract structure, which again contrasts with the informal nature of an opinion. Thus, the correct understanding of an opinion contract revolves around its inherent lack of enforceability due to the absence of consideration.