What factor does reduced visibility during adverse weather conditions impact most?

Reduced visibility during adverse weather conditions significantly affects driver reaction time. When visibility is compromised due to rain, snow, fog, or other environmental factors, a driver may not see hazards or other vehicles until it's too late, leading to delayed reactions. This slower response can make it difficult for drivers to respond to rapidly changing conditions, such as a sudden stop from the car ahead or wildlife crossing the road.

In low visibility situations, drivers often need to increase their vigilance and potentially reduce their speed, but the most immediate impact is on how quickly and effectively they can respond to situations. While other options like vehicle speed and stability are also influenced by weather, the primary concern directly related to visibility is how it affects reaction times, thus making it crucial for safety on the road in such conditions.