Final answer:
When passing is illegal, a solid yellow line is used to indicate a no-passing zone. These lines help maintain safety on roads and must be obeyed to prevent accidents.
Step-by-step explanation:
When passing is illegal, a solid yellow line is used and means you are in a no-passing zone. This road marking is critical for maintaining safety on roads, as it indicates where passing other vehicles is hazardous. Areas where a solid yellow line may be present include near sharp curves, at the crests of hills, or in locations with limited visibility. Drivers must always obey these lines to prevent accidents and ensure the orderly flow of traffic.