What is the required action for a motorist at a stop sign?

Answer: B — Come to a complete stop and yield to pedestrians and traffic

A motorist at a stop sign is required to come to a complete stop and yield to pedestrians and traffic. This is a fundamental traffic rule designed to ensure the safety of all road users. By stopping fully at the stop sign, the driver can assess the situation at the intersection and determine whether it's safe to proceed. Yielding to pedestrians and other vehicles is crucial because it allows individuals on foot to cross safely and ensures that any cars that may be approaching from other directions can be given the right of way. This action prevents potential accidents and enhances overall traffic safety. The other options do not align with safe driving practices; for instance, speeding through the stop sign disregards the right-of-way and could lead to dangerous situations. Similarly, only slowing down and looking does not guarantee that the driver is fully aware of their surroundings or that they are prepared to stop for any pedestrians or vehicles. Stopping only when traffic is present suggests an incomplete understanding of traffic signals, as the stop sign requires a full stop regardless of traffic conditions.