What does a yellow light on a traffic signal indicate for riders?

Answer: B — Prepare to stop; the light is about to turn red

A yellow light on a traffic signal serves as a warning to drivers and riders that the light is about to turn red. This signal indicates the need to prepare to stop if it's safe to do so. The intent is to give riders and drivers a chance to react appropriately. A yellow light does not mean to speed up or maintain speed; instead, it suggests that caution is necessary because the opportunity to pass safely through the intersection is quickly diminishing. This understanding is crucial for safety on the road, as many accidents occur when riders try to rush through an intersection during the yellow light phase. It emphasizes the importance of being attentive and ready to stop, rather than assuming they can continue safely through as the light changes.