Should the vehicle's speed be adjusted based on road visibility?

The question is whether speed should be adjusted to the visibility of the road. Yes - you drive only as fast as your full visibility of the road allows, regardless of speed limits - answer A.

The Road Traffic Act states that the driver of a vehicle is obliged to drive at a speed that ensures control of the vehicle, taking into account the conditions in which traffic takes place, in particular, among other things, the condition and visibility of the road. The principle is simple: you must be able to stop within the section of road that you can see ahead of you, because an obstacle may be standing just beyond its end. If at night, in fog or around a bend you can see only 40 m, and the stopping distance at 90 km/h (reaction plus braking) is about 70-80 m, you are driving too fast, even though the limit allows 90 - that is why answer A says "regardless of speed limits". Answer B is wrong: being able to see signs does not mean that you will be able to brake in time before what is beyond them. Answer C is wrong, because visibility is limited not only by darkness, but also by fog, heavy rain, bends, hills and a low sun - during the day just as after dusk.

Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)