Which traffic sign warns drivers of a school zone?

The correct answer is a pentagon-shaped sign with two children walking because this specific shape and design is standardized to indicate a school zone. The two children depicted symbolize the presence of children nearby, alerting drivers to proceed with caution. This clear visual cue is effective in increasing awareness of potential pedestrian activity, particularly during school hours when children are likely to be entering or exiting the premises.

While circular signs may indicate various things such as railroad crossings, and rectangular signs often provide information related to speed limits, these do not specifically warn of school zones. Triangular signs generally convey warning messages but are not specifically designated for school zones either. The pentagon shape, along with the image of children, makes it unmistakably clear that drivers should be vigilant in that area due to the increased likelihood of child pedestrians.