How does alcohol commonly affect a person's reaction time?

Alcohol commonly affects a person's reaction time by slowing it down. This is due to the depressant effects that alcohol has on the central nervous system. When someone consumes alcohol, it leads to impaired judgment, decreased alertness, and slower cognitive processing. This means that a person under the influence of alcohol may take longer to perceive a stimulus, evaluate the situation, and respond appropriately.

The slowing of reaction time can significantly impact driving and other activities that require quick decision-making and physical response. Therefore, even small amounts of alcohol can lead to a greater likelihood of accidents or unsafe behavior due to this impairment.

In contrast, the other options state effects such as improvements in reaction time or no effects, which do not align with the well-documented impact of alcohol on motor skills and cognitive functions. Alcohol does not enhance coordination either; rather, it disrupts the brain's functions necessary for maintaining balance and responding swiftly, further contributing to increased risk in scenarios requiring quick reactions.