You may cross a single solid white line in the highway:
- Whenever you want to
- If traffic conditions require ✓
- Only to turn into a driveway
- Only to make a u-turn
Answer: B. If traffic conditions require
You may cross a single solid white line when traffic conditions require it, such as when obstructions or traffic make the move necessary.
Why this is the answer
The handbook describes a one solid line as allowing you to pass or change lanes only when obstructions in the road or traffic conditions make it necessary. That matches the choice about traffic conditions requiring the move. It does not give you freedom to cross at any time, and it does not limit crossing to a driveway turn or a U-turn; those exceptions appear in the handbook's descriptions of other solid-line markings.
Why the other answers are wrong
- A. Whenever you want to — Crossing whenever you want ignores the handbook limit that you may do it only when obstructions or traffic conditions make it necessary.
- C. Only to turn into a driveway — Limiting a single solid line crossing to a driveway turn confuses it with the driveway exception described for other solid-line markings.
- D. Only to make a u-turn — A U-turn is not the only reason you may cross a single solid line; the handbook ties it to obstructions or traffic needs.
Remember it
Think of a single solid line as a warning to stay put unless the road or traffic gives you a real reason to cross.