What is required of a driver whose vehicle is stopped for any reason on a road?

Answer: B — Warn approaching traffic

The requirement for a driver whose vehicle is stopped on a road is to warn approaching traffic. This is crucial for ensuring the safety of both the driver and other road users. By taking steps to alert oncoming vehicles, such as turning on hazard lights or using reflective triangles, the driver helps to prevent accidents by making their presence known. This action is especially important on busy roads or highways where vehicles may not have time to react to a stationary vehicle. Failing to provide a warning puts everyone at risk, as drivers may not notice the stopped vehicle until it is too late. Other choices do not address the immediate concern of road safety as effectively. Leaving the vehicle might lead to greater risks, especially if the vehicle is in a dangerous location. Staying inside the vehicle until police arrive can lead to dangerous situations if approaching traffic does not see the vehicle. Calling for roadside assistance is often necessary, but it does not provide immediate protection for the driver or other road users while waiting for help.