What is the significance of a "medical certificate" for CDL holders?

The medical certificate is crucial for CDL holders because it certifies that the driver meets specific health standards necessary for operating a commercial vehicle. This document indicates that the driver has undergone a medical examination and has been found physically fit to handle the demands of driving a commercial vehicle. This is essential for safety, as commercial driving often involves longer hours and more rigorous conditions than standard driving.

By requiring a medical certificate, authorities ensure that only those who are physically capable of managing the responsibilities of driving large or heavy vehicles can do so, thereby reducing the risk of accidents caused by health-related issues. The other options do not pertain to the specific purpose of the medical certificate; they relate to different aspects of vehicle operation and registration.