When two or more persons enter into a contract, which of the following terms may describe the nature of that contract?

The correct answer, which describes the nature of a contract when two or more persons enter into it, is often referred to as "joint." A joint contract involves two or more parties who share the rights and responsibilities under the agreement. Each party is bound to fulfill their obligations, and they may also be equally responsible for any liabilities that arise from the contract. This type of contract ensures that all parties work together towards a common goal, and typically, each party can be individually held accountable for the entire obligation.

On the other hand, terms like "collective," "several," and "conditional" describe different aspects or types of contracts but are not the primary descriptors when identifying the nature of a contract shared by multiple parties. For example, a "collective" contract might imply a more general agreement among a group but does not specifically convey the shared obligations as with a joint contract. "Several" contracts refer more to the individual responsibilities of each party rather than a joint obligation, where each party acts independently. Lastly, "conditional" contracts involve specific conditions that must be met for the contract to be valid, which is a separate concept from the nature of the parties involved in the contract itself.