If you approach an intersection at which the traffic lights are not working, you must __________ before entering the intersection and then yield the right-of-way.

Explanation

If you approach an intersection at which the traffic lights are not working, you must treat the intersection like an all-way stop (i.e., as if there were a stop sign at each approach to the intersection). That is, you must come to a complete stop before entering the intersection, yield the right-of-way according to the rules for all-way stops, and then proceed (with extreme caution) when it's safe to do so.