During which situation should you absolutely not check your phone while driving?

Checking your phone while driving is dangerous, especially in high-traffic situations. When you're driving on a busy highway, the risk of accidents is significantly heightened due to the fast speeds and proximity of other vehicles. Your full attention is crucial in this scenario to react quickly to the actions of other drivers, lane changes, or sudden stops. Distractions, such as checking your phone, can lead to delays in reaction time and increase the likelihood of a collision.

In comparison, while stopped at a red light, it may seem less hazardous, but it's still not advisable to check your phone as it can lead to inattention when the light changes. On a straight road, the assumption might be that it is safer, but even then, distractions are risky. Driving in a parking lot involves lower speeds and fewer cars, which might seem safer to multi-task, but distractions can still result in accidents. Therefore, the paramount focus on the highway makes it the situation where checking your phone is most unacceptable.