What do domains enforce in a geodatabase?

Domains in a geodatabase are used to define a set of valid attribute values for a field within a feature class or table. This mechanism ensures that only acceptable data can be entered into specific fields, thereby maintaining data integrity and enforcing business rules related to attribute values. For example, if a domain is established for a field storing a type of land use, it might restrict entries to predefined categories such as "Residential," "Commercial," or "Industrial." This prevents errors and inconsistencies in the data, which is crucial for reliable analysis and mapping.

The other options do not accurately represent the primary function of domains. Spatial indexing pertains to how geometries are indexed for efficient spatial querying but does not restrict what values can be entered in attribute fields. Layer organization relates to how data is structured and displayed in the GIS environment but does not control attribute values. Map projections concern the transformation of geographical coordinates to a flat surface, which is unrelated to the validity of attribute values in a geodatabase.