If traffic lights at an intersection are out of order, you should...?

Answer: C — Yield to vehicles from your right

When a traffic signal is not functioning, you should treat the intersection as a four-way stop, which means that you should yield to vehicles on your right. Vehicles already at the intersection or approaching from your right have the right-of-way, so it's important to be cautious and yield to them. Proceeding with caution (A) is not enough because it may result in a collision with another vehicle. Yielding to vehicles on your left (B) is incorrect because they do not have the right-of-way in this situation. Stopping indefinitely (D) is also incorrect because you should only stop temporarily to yield to other vehicles and then proceed with caution. Remember, treat a non-functioning traffic signal as a four-way stop and always yield to vehicles on your right.