What document verifies a driver's medical fitness to operate a commercial vehicle?

The Medical Examiner's Certificate is the essential document that verifies a driver's medical fitness to operate a commercial vehicle. This certificate is issued by a licensed medical examiner who evaluates the driver's health and ensures they meet the necessary physical and mental health standards set for commercial drivers.

It serves as proof that the driver is capable of safely operating a commercial vehicle, adhering to the safety regulations established by the Federal Motor Carrier Safety Administration (FMCSA). This includes assessments of various health issues such as vision, hearing, cardiovascular health, and the absence of disqualifying conditions.

The other options do not fulfill this specific role. A driver's license primarily serves to authorize a person to drive but does not provide information about their medical condition. Vehicle registration pertains to the vehicle's legal standing and ownership rather than the driver’s health status. An insurance policy protects against financial loss but does not assess or confirm the driver's physical capability to operate a vehicle. Thus, the Medical Examiner's Certificate is the only option that directly verifies a driver's medical fitness related to commercial driving requirements.