Which law governs an association's declaration?

The correct answer is based on the understanding that an association's declaration typically falls under the realm of real estate law. This is because declarations are legal documents that govern the use, management, and regulation of property within a specific community or development, often articulated in the context of homeowners associations or condominium associations.

Real estate law encompasses various aspects concerning the ownership, use, and transaction of real property, including covenants and restrictions that are established in declarations. These legal frameworks protect both the rights of property owners and the association itself, providing formal guidelines on how properties can be used and maintained.

In this context, while contract law deals with agreements between parties and corporate law pertains to the governance of business entities, and civil law encompasses a broader range of legal issues, real estate law is specifically designed to address the regulations that govern property associations and their declarations. This makes it the most suitable choice in this scenario.