What does a solid yellow line on a roadway signify?

A solid yellow line on a roadway signifies that no passing is allowed. This marking is typically found on roads with two-way traffic and indicates that it is unsafe to cross the line to overtake another vehicle. The presence of a solid yellow line warns drivers that visibility may be limited or that conditions are not favorable for safe passing, thereby promoting safer driving practices and reducing the risk of accidents.

The other choices do not accurately reflect the meaning of a solid yellow line. For instance, passing is only permitted when safe would apply to dashed lines rather than solid lines, which specifically indicate that drivers must remain in their lane without crossing the line. Similarly, road construction signs and yield signs are unrelated to the color and type of line being discussed. Each of these would typically be indicated by different signage or markings.