How do you test the proper functioning of the air brakes?

Testing the proper functioning of air brakes is crucial for ensuring the safety and reliability of train operations. Conducting a series of brake tests, including full service and emergency applications, is the correct approach because it directly assesses how well the air brake system responds under critical conditions.

During these tests, the onboard systems evaluate the brake pressure, response times, and the overall performance of the air brakes in various scenarios. Full service applications simulate typical braking, while emergency applications test the brakes' ability to engage rapidly and effectively in sudden stop situations. This comprehensive testing helps identify any potential issues with the brake system before they lead to operational hazards.

In contrast, inspecting brake pads for wear may be a part of maintenance but does not fully evaluate the air brake system’s capacity to stop the train safely. Checking fuel levels and examining wheel alignment are also important for overall train performance, but they are unrelated to the functionality of the air brakes themselves. Thus, option B encompasses the necessary steps to ensure the air brakes are operating correctly and safely.