Why should drivers limit the use of their horn according to the Commercial Driver Handbook?

Limiting the use of the horn is emphasized in the Commercial Driver Handbook because it can startle other drivers. The horn is intended as a tool for communication on the road, particularly in situations where safety is a concern. However, excessive or unnecessary use of the horn can cause distraction or anxiety for other drivers, potentially leading to erratic behavior. By using the horn sparingly, drivers help maintain a calmer driving environment, thereby promoting safer interactions on the road.

Understanding the context of the other options provides a clearer picture. While confusion can arise from the use of a horn, it's primarily the startling effect that is seen as a more direct concern for immediate safety. Distraction and ineffectiveness are also considerations, but they do not encapsulate the central issue of startling other drivers in the same way as option B. The emphasis is thus placed on responsible and measured use of the horn to ensure clear and non-threatening communication among drivers.