How can you test for proper trailer brake functionality?

Answer: B — Activate the trailer brakes and check for response while stationary

To test for proper trailer brake functionality, activating the trailer brakes and checking for a response while stationary is a crucial method. This test involves engaging the brakes and feeling for a firm application, which indicates that the braking system is functioning correctly. Monitoring the response helps ensure that the brakes are effectively gripping without any unusual noises or irregularities, which could suggest potential issues like air leaks or malfunctioning components. By doing this test while stationary, you can assess the brakes' performance without the influence of vehicle motion, allowing for a clearer evaluation of their engagement. If the trailer brakes do not respond properly or the pedal feels soft, further inspection is warranted to diagnose any problems. While checking tire pressure, driving at slow speeds to observe performance, or inspecting brake lights are all important vehicle checks, they do not specifically focus on the functionality of the trailer brakes themselves in the same direct way as the proper engagement test does.