How does alcohol affect a driver’s ability to respond to sudden changes in traffic conditions?

B is the correct answer because alcohol has been shown to significantly impair a person's reaction time and overall cognitive functions. When a driver consumes alcohol, their ability to process information, make decisions, and respond quickly to unexpected changes in traffic, such as sudden stops or obstacles, is diminished. This impairment can lead to delayed responses, which can be dangerous on the road.

In contrast, the other options suggest improvements or no impact from alcohol on a driver's responses, which is inaccurate. Alcohol does not enhance reflexes or allow for quick adjustments; rather, it adversely affects a driver’s capacity to react appropriately to sudden traffic conditions. Understanding the effects of alcohol on driving is crucial for roadway safety and reducing the risk of accidents.