Class A may inspect trailers and semi-trailers if they are:

Class A inspectors are authorized to inspect trailers and semi-trailers, but there are specific conditions under which they can perform these inspections. The correct answer is based on the understanding of vehicle weight classifications and braking systems.

Trailers and semi-trailers that are not equipped with air brakes fall under a category that Class A inspectors are allowed to inspect. This is primarily because trailers and semi-trailers equipped with air brakes typically require a higher level of inspection due to the added complexities of air brake systems. By restricting the inspections to those units not equipped with air brakes, the regulations ensure that only simpler systems are handled by inspectors without specialized training in air brake operation and maintenance.

This delineation is crucial as it safeguards road safety by ensuring that qualified personnel handle more complex vehicle systems requiring specific expertise. Consequently, options related to weight limitations or registration status do not apply to the ability of a Class A inspector to inspect trailers and semi-trailers. The focus on braking systems highlights the importance of proper training and knowledge in maintaining vehicle safety standards.