If a large vehicle in front of you does not have its brake light on

1. it is definitely not slowing down.
2. it could still be slowing down without using the brakes. ✓
3. it is slowing down.
4. None of the above

Answer: B. it could still be slowing down without using the brakes.

It could still be slowing down without using the brakes.

Why this is the answer

The handbook explains that many large vehicles have engine retarders that slow them down without the brakes, and truck drivers also use their gears to slow down. So a truck or bus ahead of you may be slowing even when no brake light shows. The handbook tells you to look ahead and listen for a change in the engine noise, and to watch for other clues. A dark brake light therefore does not prove the vehicle is holding its speed.

Why the other answers are wrong

• A. it is definitely not slowing down. — This is wrong because the handbook says a large vehicle can be slowing without brake lights, so no brake light does not prove it is keeping its speed.
• C. it is slowing down. — A missing brake light does not confirm slowing either; the point is that you cannot tell from the brake light alone, so you should look and listen for other clues.
• D. None of the above — This is wrong because the passages do give a real answer: the vehicle may be slowing down by other means even with no brake light showing.

Remember it

Large trucks and buses can shed speed with engine and gears, so read the whole vehicle, not just the brake light.