Which abbreviation indicates common terms used by regulatory agencies for licensing?

The abbreviation that indicates common terms used by regulatory agencies for licensing is CDL, which stands for Commercial Driver’s License. This license is specifically for individuals who operate large or heavy vehicles such as trucks and buses, and its standards and regulations are established by federal and state agencies.

The other options, like DDL, DIS, and EMER, do not represent widely recognized terms associated with licensing regulations for commercial drivers. DDL could refer to a variety of other contexts, DIS is more aligned with disciplines like information systems, and EMER typically refers to emergency contexts rather than licensing. Therefore, CDL is the most appropriate answer in this context, reflecting the specific licensing requirements for commercial vehicle operators.