Which of the following actions should be performed while driving a passenger car and overtaking in a fog outside the built-up area?

Why?

When overtaking in fog outside a built-up area, you must give short horn signals to alert others to your presence. Flashing your headlights does not replace this requirement, so A is incorrect. C is incorrect because rear fog lights may be used only when visibility falls below 50 metres.

art. 30 ust. 1 pkt 1 lit. b i ust. 3 Prawa o ruchu drogowym