Final answer:
A Class D license is a non-commercial driver's license allowing the operation of passenger vehicles but does not permit driving commercial vehicles like semi-trucks, buses, or those that carry hazardous materials, which require a CDL.
Step-by-step explanation:
The question presented concerns what type of vehicles cannot be driven by someone with a Class D license. In the United States, a Class D license is typically a standard non-commercial driver's license, which allows the operation of most passenger vehicles such as cars, light trucks, and small vans.
However, holders of a Class D license are not permitted to drive certain single-unit vehicles. Specifically, they are not allowed to drive commercial vehicles that require a Commercial Driver's License (CDL), such as semi-trucks, buses, and vehicles that carry hazardous materials or exceed a certain weight and size specified by state regulations.
It’s important to note that regulations may vary by state, so one should check local laws for the most accurate information. Moreover, some states might have different classifications or designations for their driver's licenses.