Which system helps to maintain control of a vehicle during normal operation?

The service brake system is vital for maintaining control of a vehicle during normal operation. It provides the necessary stopping power to safely slow down or stop the vehicle as needed. This system includes components such as the brake pads, rotors, calipers, and the brake pedal, all of which work together to ensure that the driver can effectively manage the vehicle's speed and respond to road conditions.

While power steering assists in steering and making it easier to maneuver the vehicle, it does not directly address stopping the vehicle. The parking brake system is primarily intended for securing a stationary vehicle and is not used during normal driving conditions. Similarly, while the suspension system plays a crucial role in ride comfort and vehicle stability, it does not aid in braking or controlling the vehicle's speed during operation.

Therefore, the service brake system is specifically designed to maintain control by enabling the driver to slow or stop the vehicle safely when necessary, which is why it is the correct answer in this context.