What element of the listing agreement is critical for its validity?

A critical element of a listing agreement that ensures its validity is the inclusion of a specified expiration date. This requirement is in place to delineate the time frame during which the listing agent has the authority to act on behalf of the seller. By establishing a clear expiration date, both parties—seller and agent—agree on the duration of the contract, which helps avoid misunderstandings and potential disputes.

In listing agreements, if there is no specific expiration date, it can lead to issues concerning the ongoing obligations of both parties. Without this detail, the agreement may be seen as open-ended, which can complicate the relationship and legal standing of both the seller and the agent. This clarity is essential for legal enforceability and helps to manage expectations appropriately.

The other choices do not constitute essential validity requirements. While it is important for the agent to sign the agreement and to list all parties involved, these factors alone do not determine the contractual nature of the listing. Moreover, listing multiple expiration dates is unnecessary and could lead to confusion, rather than providing clarity regarding the agreement's duration. Thus, the most critical element for the validity of a listing agreement is indeed the clear specification of a single expiration date.