If you encounter a traffic signal that is not functioning, what should you do?

Answer: C — Treat it as a four-way stop

When encountering a non-functioning traffic signal, treating it as a four-way stop is the correct approach to ensure safety and maintain order at the intersection. This means that all vehicles must come to a complete stop before proceeding. The standard rules for a four-way stop apply, which generally means that the first vehicle to arrive at the intersection has the right-of-way, and if two vehicles arrive simultaneously, the vehicle on the right has the right-of-way. This procedure helps prevent confusion and potential accidents by establishing clear right-of-way rules when traffic signals are out. Understanding this principle is crucial, as it ensures that drivers are prepared to navigate the intersection safely, thereby reducing the likelihood of collisions. Other options, such as proceeding without stopping or treating the situation as a yield sign, do not provide the necessary caution and could lead to dangerous situations. Calling for help may be appropriate in some situations, but it does not address the immediate need for traffic control at the intersection. Thus, recognizing the need to act as if the signal does not exist and following the four-way stop rules is essential for safe driving.