Which of the following best describes marijuana's impact on driving?

• A. Slow reaction time, interfere with concentration, and impact perception of time and distance
• B. It speeds up reaction time
• C. It has no impact
• D. It only affects vision

Answer: (A)

Marijuana’s impact on driving comes from its broad effect on thinking, attention, and perception, not just what you see. It tends to slow reaction time, making it take longer to respond to hazards or changes in traffic. It also reduces the ability to concentrate and hold attention on the task of driving, which can lead to missed cues or delayed decisions. In addition, marijuana can distort the perception of time and distance, so judging how far ahead other vehicles are or how fast they’re moving becomes more uncertain. All of these together increase the risk of crashing.

The other ideas don’t fit because marijuana does not speed up reaction time, it does have a clear impact on driving—beyond vision alone—and its effects aren’t limited to vision. The impairment can also depend on dose and individual factors.