In the context of stress and driving, a driver is impaired when they:

• A. are fully alert and calm while driving
• B. have recently completed a stress management course
• C. are unable to concentrate due to high levels of stress
• D. are listening to relaxing music in the car

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the context of the problem, which is about how stress affects driving performance.
2. Step 2: Recognize that being fully alert and calm while driving generally indicates good driving conditions, so this would not impair the driver.
3. Step 3: Note that completing a stress management course is likely to improve a driver's ability to handle stress, so this would not cause impairment.
4. Step 4: Identify that high levels of stress can impair cognitive functions such as concentration, which is critical for safe driving.
5. Step 5: Understand that listening to relaxing music typically helps reduce stress and does not impair driving; therefore, the impairment is specifically linked to being unable to concentrate due to high stress.