Final answer:
A Class 1 licence does not permit the operation of a motorcycle; thus, a driver with this licence cannot legally operate a motorcycle without the appropriate motorcycle-specific licence.
Step-by-step explanation:
A driver with a Class 1 licence is not able to operate a motorcycle. Class 1 licences typically cover the operation of large commercial vehicles such as tractor-trailers, but do not include motorcycles, which usually require a specific type of licence. Therefore, among the given options: a motorcycle, a passenger vehicle, a school bus, and a heavy truck with air brakes, a motorcycle (option a) is the vehicle that a driver with a Class 1 licence is not permitted to operate without the appropriate motorcycle-specific licence.