Which of the following is considered part of a car's control system?

The steering wheel is an essential component of a car's control system because it directly influences the direction of the vehicle. By turning the steering wheel, the driver can maneuver the car left or right, making it a critical tool for controlling the vehicle's movement and ensuring safe navigation on the road.

In contrast, while the seatbelt plays a crucial role in passenger safety by restraining occupants during a collision, it does not contribute to the physical control of the car. Windshield wipers are important for visibility in adverse weather conditions but similarly do not affect the vehicle's operational control. The radio, while providing entertainment and information, is unrelated to driving and is not a control system element. Overall, the steering wheel's function as a direct mechanism for steering makes it the correct part of a car's control system.