Why should you regularly apply the brakes with force at standstill?

Your answer is correct. Regularly applying the brakes with force while the vehicle is at a standstill helps check two important things: first, it ensures that the mechanical parts of the transmission and the connections to the braking system are working properly, as you can feel if something is loose or not engaging correctly. Second, it helps detect any leaks in the hydraulic braking system, which is vital for maintaining consistent brake pressure and safe stopping ability. This preventive action helps identify potential brake problems early, ensuring the vehicle remains safe to drive. The third option about deceleration does not apply here because deceleration can only be tested when the vehicle is moving, not at a standstill.