Which of the following factors may NOT affect an individual's ability to operate a motor vehicle safely?

Slurred speech is often an indicator of impairment, particularly from substances like alcohol or drugs, which can significantly affect an individual's ability to operate a motor vehicle safely. When drivers exhibit slurred speech, it typically suggests a level of intoxication or neurological impairment that compromises their cognitive and motor functions.

Fatigue can severely impact a driver's attention and reaction time, potentially leading to accidents and unsafe driving conditions. It causes drowsiness, reduces alertness, and impairs critical thinking.

Slowed reaction time is another crucial factor, as it directly influences how quickly a driver can respond to changing traffic conditions or unexpected hazards. This can significantly increase the risk of collisions.

Inattentiveness to surroundings is equally important, as drivers who are distracted—whether by their phones, passengers, or other stimuli—may fail to notice important cues that are essential for safe driving.

Given this context, the choice suggesting that slurred speech may not affect driving safety overlooks the critical role that observable signs of impairment play in assessing a driver's ability to operate a vehicle.