Which of the following is not a factor that can affect a driver's mental alertness?

Answer: A — Listening to music

Listening to music can actually affect a driver's mental alertness, as it can be distracting and cause the driver to become less focused on the road. Daydreaming and not drinking enough water can also have a negative impact on a driver's mental alertness. Eating a healthy snack, however, can actually improve a driver's mental alertness by providing essential nutrients and energy.