What does a solid yellow line indicate on the road?

A solid yellow line on the road primarily indicates that no passing is allowed. This marking is used to prevent vehicles from crossing into the opposing lane where visibility might be poor or where it's unsafe to pass due to road conditions, curves, or other factors. It serves as a warning to drivers to stay in their lane and maintain a safe distance from oncoming traffic. Understanding this helps enhance road safety, as obeying these markings can reduce the likelihood of collisions that might occur from unauthorized lane changes or passing maneuvers.

The other options suggest actions that are either prohibited or misleading. For example, a solid yellow line does not permit passing, contradicting the notion of passing being allowed or encouraged. Furthermore, while construction zones may have their specific markings, a solid yellow line does not specifically signify construction ahead, nor does it imply that lane changing is encouraged. Thus, recognizing the significance of solid yellow lines is crucial for safe driving practices.