What action should a driver take when the low-pressure warning device is activated?

Answer: B — Stop immediately

When the low-pressure warning device is activated, it indicates that the air brake system's pressure has dropped below a safe level. This warning is a critical safety feature designed to alert the driver that the braking system may be compromised. Stopping immediately is the appropriate action in this scenario because a loss of air pressure could lead to brake failure, making it extremely dangerous to continue driving. By halting the vehicle, the driver can assess the situation safely and take necessary measures, such as contacting a technician for repairs or troubleshooting the air brake system before resuming operation. Engaging in alternative actions, such as checking brake fluid, increasing speed, or continuing to drive, would not address the urgent issue posed by low brake pressure and could potentially lead to a severe accident or loss of vehicle control. Taking immediate action to stop ensures the safety of the driver and others on the road.