The master cylinder uses hydraulic pressure to operate which unit(s)? a. Wheel brake b. Steering wheel c. Front wheels d. Input piston

The correct answer is a. Wheel brake.The master cylinder is a crucial component in a vehicle's braking system. It generates hydraulic pressure when the brake pedal is pressed, which then operates the wheel brakes. The hydraulic pressure is transmitted through the brake lines to the wheel brakes, causing the brake pads or shoes to press against the brake rotors or drums, resulting in the vehicle coming to a stop.