You are driving through a heavy rain shower on the road to the ferry terminal in Breskens. Visibility is poor, the road surface is mirror-slick from the water. May you switch on your rear fog light now?
No, the rear fog light may not be used in rain, not even heavy rain
Yes, with such poor visibility it is allowed, just like in fog
Explanation
Wrong — trap: fog solution applied to rain. You may never use the rear fog light in rain, however heavy; it is reserved for very dense fog or heavy snowfall (Book p.188).