What is the function of a stop sign?

Answer: C — To require vehicles to come to a complete stop

The primary function of a stop sign is to require vehicles to come to a complete stop at the designated intersection. This regulation is crucial for ensuring safety and order on the road. When a driver approaches a stop sign, they must halt their vehicle before proceeding, allowing them to look for oncoming traffic or pedestrians and ensure it is safe to continue. This practice helps prevent accidents and facilitates smoother traffic flow at intersections where visibility might be limited or where multiple roads converge. The other options relate to different traffic control functions. While they describe important aspects of traffic signage, they do not accurately capture the specific and critical role that a stop sign plays in driving regulations.