A yellow arrow means what for the indicated lane of traffic?

A yellow arrow signals that drivers should prepare to stop and is an indication similar to a circular yellow light. This means that while the signal is active, drivers in the indicated lane should not proceed because the light will soon change to red. It serves to warn drivers that the right of way is shifting and they need to be cautious about their next actions.

Option B is correct because it conveys that a yellow arrow functions similarly to a circular yellow light; both signal that the driver must slow down and be prepared for the possibility of the light turning red, marking a change in traffic direction and right of way.

The other options do not accurately reflect the function of a yellow arrow. For example, saying that it is never used as a traffic signal is incorrect, as yellow arrows are commonly used to indicate the state of traffic flow at intersections. The statement suggesting that drivers may go in the direction indicated by the arrow misinterprets the caution that the yellow arrow presents and could lead to unsafe driving behavior. Finally, while a yellow arrow does signal a change is imminent, it is misleading to say it is exclusively warning of a green arrow's approach, as that does not encompass the full meaning of the yellow arrow signal on its own.