What does a diamond-shaped sign that states 'School Bus Stop Ahead' indicate?

The diamond-shaped sign indicating 'School Bus Stop Ahead' is specifically designed to alert drivers that they are approaching an area where a school bus will be stopping to pick up or drop off children. This type of sign is important for enhancing safety by preparing drivers to slow down and be cautious, as children may be crossing the street in the vicinity of the bus.

In differentiating from other options, the sign does not signal a pedestrian crossing, reduced speed zone, or a general school zone. While a pedestrian crossing sign focuses on the presence of foot traffic and a school zone sign implies a general area with children, the specific wording of 'School Bus Stop Ahead' clearly indicates the need to pay attention for school bus activity. Thus, the emphasis on school buses makes the answer B the most accurate and relevant choice.