Final answer:
The activity that should occur at the 500-hour maintenance time interval is inspecting and adjusting brakes.
Thus, the correct option is c.
Step-by-step explanation:
The activity that should occur at the 500-hour maintenance time interval is c) Inspecting and adjusting brakes.
Inspecting and adjusting brakes is an important maintenance task for vehicles to ensure they are functioning properly and to prevent accidents.
A regular inspection and adjustment of brakes can help identify any wear and tear, damaged components, or adjustments needed to maintain their effectiveness. Changing light bulbs, checking email, and watching a movie are not relevant to the 500-hour maintenance time interval for vehicles.
Therefore, the correct option is c) Inspecting and adjusting brakes