Which of the following is a requirement for a valid real estate contract?

A valid real estate contract must contain a legal purpose, meaning that the contract's objectives and terms must comply with the law and public policy. This requirement ensures that the agreement does not involve illegal activities, such as agreements for selling illegal substances or properties where the transaction would contravene local zoning laws. Establishing a legal purpose is critical because a contract involving unlawful actions is inherently void and unenforceable.

In contrast, the other options do not represent necessary elements for the validity of a real estate contract. For instance, a real estate contract can be valid even if it is not verbal; often, written contracts are preferred for clarity and legal standing but verbal agreements can also be enforceable in certain situations. Moreover, not all parties involved in a real estate transaction need to be licensed agents; parties can be individuals entering into contracts without agent representation. Lastly, there is no strict requirement for a contract to be executed within a specific timeframe like 30 days to maintain its validity; timelines may apply to certain obligations within the contract but do not pertain to the contract’s legality itself.