Final answer:
The color of a school zone sign is B. yellow, which is used for its high visibility and is standard for warning signs related to school zones.
Step-by-step explanation:
The color of a school zone sign is B. yellow, which is used for its high visibility and is standard for warning signs related to school zones. The color of a school zone sign is important for ensuring the safety of students as it needs to be highly visible to drivers passing by. When it comes to the options given, which are A. red, B. yellow, C. white, D. blue, the correct answer is B. yellow. School zone signs are designed to be bright and noticeable, and yellow is a color commonly used for warning signs because it is easily visible from a distance and in various lighting conditions.