The rear fog lamp:
- It is obligatory to install fog lights in buses only.
- Is turned-on automatically when it is foggy.
- Correct answer: the rear fog lights can only be turned on if the front lights are on.
- Is turned-on only while driving in reverse.
Why this is the answer
The correct answer in the official bank: the rear fog lights can only be turned on if the front lights are on.
The rear fog lamp is wired so that it can only be switched on when the front lights are on, because it is meant to work together with the normal lighting in poor visibility. The driver turns it on manually; it does not switch on by itself in fog, and it has nothing to do with reversing, which uses the reversing lamp. Use it only in thick fog or very poor visibility, and turn it off afterwards so it does not dazzle drivers behind.