Final answer:
At a flashing red traffic signal, you must stop before entering the intersection and proceed when it is safe to do so, treating it like a stop sign.
Step-by-step explanation:
When approaching an intersection and the traffic signal light is flashing red, the correct action to take is to stop before entering, and then proceed when safe. This flashing red light is treated as a stop sign, meaning that all drivers must come to a complete stop, check for oncoming traffic, and for pedestrians, and only continue through the intersection when it is safe to do so. It's important to exercise caution as many accidents occur when drivers fail to observe this rule.