What does a solid line in the center of a roadway indicate?

Answer: B — No passing is allowed

A solid line in the center of a roadway serves as a critical traffic control measure indicating that no passing is allowed. This marking is used to promote safety on the roads, particularly in areas where visibility is poor or where it's important to maintain safe distances from oncoming traffic. When a solid line is present, it signifies to drivers that overtaking another vehicle is prohibited due to potential hazards, such as curves, intersections, or other areas that could pose a danger if passing were attempted. Adhering to this rule helps prevent accidents and ensures the smooth flow of traffic, as drivers are expected to remain within their lane and not engage in passing maneuvers.