What action should a driver take upon experiencing a loss of pressure while driving?

Answer: C — Pull over immediately and check the brake system

Upon experiencing a loss of pressure while driving, the appropriate action is to pull over immediately and check the brake system. A loss of pressure in the air brake system can indicate a critical failure or leak that jeopardizes the vehicle's ability to stop safely. Immediate action is necessary to prevent potential accidents or loss of control. By pulling over as soon as it is safe to do so, the driver can assess the situation and determine the next steps, which may include checking for visible leaks, assessing the condition of the brake components, or safely shutting down the vehicle. Addressing this issue promptly ensures not only the safety of the driver but also the safety of others on the road. Other options involve either inaction or unrelated tasks. Ignoring the issue could lead to a significant danger, checking the fuel gauge wouldn't address the loss of brake pressure, and calling for roadside assistance may be necessary later, but the immediate priority is to ensure the vehicle is safe to operate.