What does a solid double yellow line indicate?

• A. A shared center line
• B. A lane for bicycles only
• C. A no-passing zone; you must not cross to pass another vehicle.
• D. A road shoulder ahead

Answer: (C)

A solid double yellow line marks a no-passing zone for traffic traveling in both directions. It keeps opposing drivers from crossing these lines to pass one another, which reduces the risk of head-on collisions on two‑lane roads. The line is there to control passing, not to designate bicycle lanes or shoulders. The main exception is turning left: you may cross the lines to complete a left turn into a private road or driveway when it’s safe, but you still must not pass another vehicle by crossing these lines.