Which system in a vehicle uses hydraulic force to transmit motion?

The braking system in a vehicle uses hydraulic force to transmit motion, making it the correct choice. This system operates on the principle of hydraulics, where brake fluid is used to transmit the driver's foot pressure on the brake pedal to the brake components at each wheel. When the brake pedal is pressed, it creates pressure in the brake lines, which forces the brake calipers or wheel cylinders to engage the brake pads or shoes. This engagement slows down or stops the vehicle by creating friction against the brake rotors or drums.

The steering system, while it may also use hydraulic mechanisms (like in power steering), primarily functions to direct the vehicle rather than transmit motion in the same way the braking system does. The suspension system supports the vehicle's weight and absorbs bumps but does not solely rely on hydraulic force to transmit motion. The fuel system's role is to deliver fuel to the engine and does not involve motion transmission in a hydraulic sense.