What must a driver ensure regarding the vacuum gauge while driving?

The correct answer focuses on the importance of monitoring the vacuum gauge frequently for readings. This gauge plays a crucial role in providing real-time information about the engine's vacuum levels, which can indicate the efficiency and performance of the engine, as well as alert the driver to potential issues. Regular checks on the vacuum gauge allow drivers to detect abnormalities early, such as leaks or failures in the intake system, helping to ensure optimal operation and prevent more significant mechanical problems.

Monitoring the gauge frequently is vital for safe driving and vehicle maintenance. It helps the driver stay informed about the vehicle’s performance and can be an early warning system for issues that could affect the overall safety and reliability of the vehicle.