What does a solid double yellow line indicate?

A solid double yellow line indicates that no passing is allowed in either direction. This road marking serves as a warning to drivers that the lane separation signifies a zone where it is unsafe to overtake other vehicles. The presence of the double yellow line typically indicates a higher potential for oncoming traffic or other hazards, which is why the rule is enforced for the safety of all road users.

The other choices suggest various scenarios in which passing might be possible, which contradicts the meaning of a solid double yellow line. Thus, understanding this traffic marking is crucial for safe driving practices and adherence to road regulations.