What steps should be taken after running the engine for cut-in and cut-out pressure tests?

Answer: B — Monitor the air pressure gauge

Monitoring the air pressure gauge after running the engine for cut-in and cut-out pressure tests is crucial for ensuring that the air brake system is functioning properly. The cut-in pressure is the point at which the air compressor kicks in to add air to the system, while the cut-out pressure is the point at which the compressor stops. By watching the pressure gauge, you can confirm that the system is maintaining the correct pressure levels during operation. A drop in pressure could indicate a leak in the system or that the compressor is not working effectively, which could lead to brake failure. Therefore, continuous monitoring of the air pressure gauge ensures the integrity and safety of the braking system before operating the vehicle on the road. This step is essential for safe vehicle operation and is a standard practice in the pre-trip inspection process.