Drive below the posted speed limit when:

1. Anything makes conditions less than perfect. ✓
2. You see a police car.
3. Entering a highway where there are other cars.
4. You are on a four-lane road.

Answer: A. Anything makes conditions less than perfect.

You should drive below the posted speed limit when anything makes conditions less than perfect, such as bad weather, heavy traffic, or low visibility.

Why this is the answer

The handbook says posted limits are meant for normal driving conditions. When traffic is heavy, weather is bad, visibility is low, or other driving conditions are poor, you must adjust your speed and following distance to help avoid crashes. That supports slowing below the posted limit when conditions are not perfect, rather than treating the limit as a speed you must always reach.

Why the other answers are wrong

• B. You see a police car. — Seeing a police car is not listed as a reason to drive below the posted limit; the handbook only gives specific steps near a stopped emergency vehicle with lights activated.
• C. Entering a highway where there are other cars. — Entering a highway where other cars are present does not by itself mean conditions are poor enough to require driving below the posted limit.
• D. You are on a four-lane road. — Being on a four-lane road is not a condition the handbook says requires a lower speed; the passages do not tie lane count to driving below the limit.

Remember it

Treat the posted limit as a maximum for good conditions, not a speed you must always drive when things get worse.