Final answer:
To detect leakage in a hydraulic brake system, pumping the brake three times and holding the pedal down for 5 seconds is the correct option.
Step-by-step explanation:
The correct answer to detecting leakage in a hydraulic brake system is A. Pumping the brake three times and holding the pedal down for 5 seconds.
This process is known as the brake pedal depression test. By pumping the brake pedal three times and then holding it down for around 5 seconds, you build up pressure in the system. If there's a leakage in the hydraulic brake system, the pedal will gradually sink toward the floor due to the loss of pressure. If the pedal remains firm without sinking, it indicates that the system pressure is being maintained, suggesting that there's no significant leak in the brake system.
Options B, C, and D don't directly relate to detecting leakage in the hydraulic brake system. Turning the steering wheel sharply left and right (option B) primarily checks power steering performance. Honking the horn repeatedly (option C) and engaging the parking brake while driving (option D) are unrelated to checking for brake system leaks and could potentially be unsafe actions.