What action must a driver take when there is a flashing yellow light?

Answer: C — Yield if necessary

When encountering a flashing yellow light, a driver is required to yield if necessary. This signal indicates that drivers should approach with caution and be prepared to stop if there are any hazards present. Unlike a steady yellow light, which warns of an upcoming red signal, a flashing yellow light specifically denotes that drivers should still proceed, but with increased awareness of their surroundings and potential obstacles, such as pedestrians or other vehicles. This means that while the driver does not have to come to a complete stop, they must remain attentive and yield the right of way when required, ensuring safe passage through the intersection.