Final answer:
The passenger should sit on the seat with the motorcycle rider to properly adjust the mirrors before riding, ensuring both have a clear view of the road and potential hazards. So, the correct answer is option c.
Step-by-step explanation:
When adjusting your mirrors to carry a passenger on a motorcycle, the correct procedure is for the passenger to sit on the seat with you. This is because the weight of the passenger will alter the riding dynamics of the motorcycle, including the mirror angles. As such, you should sit on the motorcycle in the riding position, and have the passenger sit behind you as they would when you are actually riding.
By doing so, you can adjust the mirrors to ensure that both you and your passenger have a clear view of the road behind and any potential hazards. It's crucial to make mirror adjustments before starting your ride for optimal safety. So, the correct answer is option c.