How many commercial licenses are drivers allowed to hold according to federal regulations?

Federal regulations stipulate that drivers may hold only one commercial driver's license (CDL) at a time. This rule is established to ensure that there is accountability and a clear record of a driver's qualifications and driving history. Having multiple CDLs could lead to confusion regarding a driver's credentials and make it more challenging for authorities to track infractions or violations effectively.

Maintaining a single license also simplifies the process for compliance with the various state and federal laws that govern commercial driving. It helps ensure that licensing agencies can monitor driver performance and safety standards, which is critical in maintaining road safety.

The other options imply either multiple licenses or none at all, which contradicts the established regulations that prioritize safety and organized record-keeping in the transportation industry.