How should you check the parking brake?

Answer: C — Put the vehicle in gear while the parking brake is on

It is important to check the parking brake by placing the vehicle in gear while the brake is engaged because this simulates the conditions when the vehicle is parked and will ensure the brake is working properly. Option A is incorrect because simply releasing the brake and ensuring the vehicle does not move does not guarantee that the brake is functioning correctly. Option B is incorrect because accelerating the vehicle could cause the brake to disengage and the vehicle to move, leading to dangerous situations. Option D is also incorrect because manually inspecting the brake mechanism may not provide an accurate assessment of its functionality.