When driving downhill, it is best to put the car in low gear as the car’s engine would be your brake instead of the car’s. A lower gear has a bigger gear compared to the higher gears so it would take more time to rotate and will avoid your car to move fast.
The engine can handle the gravity more than the brake as the engine has a cooling and lubricating system which the brake lacks. The low gears must be used when going downhill to provide extra stopping power to the brake and they are also advised to use uphill to avoid getting the machine died in the middle of the climb.
Option C - downshift and use the motor to assist in slowing down.
Do not place the gearshift in neutral, use a low gear to help slow down your vehicle. Do not apply brakes while descending a steep hill in a vehicle, your brakes can over heat them which may lead to brake failure.