If there are one or two solid yellow lines at the center of the road, what are you not allowed to do?

When there are one or two solid yellow lines at the center of the road, they indicate that passing in the oncoming lane is prohibited. Solid yellow lines signify that it is unsafe to overtake another vehicle, typically because of visibility issues, curves, or other conditions that would make it dangerous to change lanes. Therefore, if you encounter these markings, you must remain in your lane and cannot cross those lines to pass another vehicle. This rule is crucial for maintaining safety on the road, as it helps prevent accidents that can happen from risky maneuvers in areas where visibility or road conditions are inadequate.

The other choices, while related to road safety, do not directly pertain to the implications of solid yellow lines. Making a U-turn, changing lanes, or driving above the speed limit are governed by different traffic regulations and do not specifically relate to the prohibition of passing in areas marked by solid yellow lines.