What is a common risk when a combination vehicle's air system is malfunctioning?

When a combination vehicle's air system is malfunctioning, there is an increased risk of brake failure. The air brake system in combination vehicles relies on compressed air to operate efficiently. If there is a malfunction in the air system, it can lead to insufficient air pressure, which is crucial for the proper functioning of the brakes. This deficiency could result in the brakes not applying correctly or potentially failing altogether, creating a hazardous situation while driving.

In contrast, the other options do not accurately represent the implications of a malfunctioning air system. Enhanced fuel efficiency, for instance, does not relate to the braking system or vehicle safety. Improved visibility does not stem from any aspect of air system functionality, and the idea that such malfunctions pose no risk is incorrect, as they directly jeopardize vehicle control and safety. Understanding the air system's critical role in braking helps highlight the seriousness of any malfunction.