Introduction:
The question pertains to the effects of alcohol consumption on driving abilities. It specifically asks about the impact of alcohol on an intelligent driver. In this context, we will explore the different possibilities and explain why an increase in reaction time is the correct answer.

Alcohol's Effect on Driving Abilities:
Alcohol is a depressant that affects the central nervous system, impairing various cognitive and physical functions. When consumed, it can lead to a range of negative effects on driving abilities, including decreased coordination, concentration, and judgment. These impairments can significantly impact a driver's performance and reaction time.

Increased Alertness:
Alcohol consumption does not increase alertness. On the contrary, it tends to decrease alertness and attentiveness. This is because alcohol affects the brain's ability to process information and respond to external stimuli effectively. Therefore, option A is incorrect.

Increased Speed:
Alcohol consumption can lead to a false sense of confidence and overestimation of one's abilities. This may result in a driver exceeding the speed limit or engaging in reckless driving behaviors. However, it is important to note that alcohol does not directly increase a driver's speed. Therefore, option C is incorrect.

Increased Judgment:
Alcohol impairs judgment and decision-making abilities. It affects a person's ability to assess situations accurately and make appropriate choices. Therefore, option D is incorrect.

Increase in Reaction Time:
Alcohol slows down the brain's processing speed and impairs coordination. These effects directly impact a driver's reaction time, making it slower than normal. This means that when faced with unexpected events or hazards on the road, an intoxicated driver will take longer to respond and make necessary adjustments. Option B is the correct answer as it accurately reflects the impact of alcohol on an intelligent driver's reaction time.

Conclusion:
Alcohol consumption negatively affects driving abilities, impairing various cognitive and physical functions. It does not increase alertness, speed, or judgment. Instead, it slows down reaction time, making it longer than normal. It is crucial to understand the dangers of driving under the influence of alcohol and prioritize responsible and sober driving to ensure road safety for oneself and others.