During the day, in dense fog, which lights must you turn on?

Why this is the correct answer

In dense fog during the day, you must turn on the following lights: 1. DIPPED-BEAM HEADLIGHTS (low beam) — MANDATORY. Whenever visibility is significantly reduced (fog, heavy rain, snow, etc.), you must use at least dipped-beam headlights. Daytime running lights (DRL) are NOT enough. 2. FRONT FOG LIGHT — OPTIONAL. You may use it to improve near-road visibility. It can be used alone or together with dipped-beam headlights. It is recommended but not required. 3. REAR FOG LIGHT — MANDATORY in dense fog. When conditions are especially adverse (dense fog, very heavy rain, heavy snowfall, thick clouds of dust or smoke), the rear fog light MUST be switched on. Its intense red light makes your vehicle visible to drivers behind you. You must turn it off as soon as conditions improve, because it can dazzle following drivers. IMPORTANT: Never use high beams in fog — the light reflects off water droplets and actually reduces your visibility (mirror effect). Summary: Dipped-beam = always mandatory in fog | Front fog light = optional | Rear fog light = mandatory in DENSE fog | High beams = never in fog | DRL alone = not sufficient.