You may cross a single solid white line on the highway:
- Whenever you want to.
- If traffic conditions require you to do so. ✓
- Only to turn into a driveway.
- Only to make a U-turn.
Answer: B. If traffic conditions require you to do so.
You may cross a single solid white line when obstructions or traffic conditions make it necessary.
Why this is the answer
The handbook's pavement-marking section says a single solid line can be crossed to pass or change lanes only when obstructions or traffic conditions make it necessary. That makes the traffic-conditions choice the right one. The manual does not give a free pass to cross whenever you feel like it, and it does not limit a single solid line crossing to driveway turns or U-turns. Those turn exceptions belong to other solid-line situations described in the markings section.
Why the other answers are wrong
- A. Whenever you want to. — Crossing whenever you want ignores the handbook's condition that a single solid line may be crossed 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 is wrong; the handbook allows crossing when road obstructions or traffic conditions require it, and driveway-turn language applies to 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 manual ties that crossing to obstructions or traffic conditions, not to U-turns.
Remember it
Think of a single solid white line as a conditions line: you cross it because the road or traffic requires it, not because you want to.