Which of the following should be avoided when driving a commercial vehicle?

Answer: A — Adjusting mirrors while driving

Adjusting mirrors while driving is something that should be avoided because it diverts your attention from the road and increases the risk of an accident. When driving a commercial vehicle, maintaining full focus on the surrounding conditions is crucial due to the size and weight of the vehicle, which require more careful maneuvering. Frequent adjustments to mirrors can lead to distractions that could cause you to miss important visual cues from other vehicles or pedestrians. Instead, you should ensure that your mirrors are properly adjusted before starting your trip, allowing you to drive safely without needing to make such adjustments while on the road. Maintaining consistent speed, using a hands-free device, and staying aware of surroundings are all practices that enhance safety and control in driving a commercial vehicle.