When brakes become overheated, they also become
- dangerously inefficient. ✓
- shiny.
- more efficient.
- wet.
Answer: A. dangerously inefficient.
Overheated brakes become dangerously inefficient, so you must avoid excessive use of brakes on long downgrades.
Why this is the answer
The handbook warns that overheated brakes are dangerously inefficient and tells you to take great care to avoid excessive braking on long downgrades. It points you to engine braking as the main way to control speed on a long grade, and suggests choosing your gear before you start down so you aren't caught hunting for a shift. The heat takes away the braking performance you are counting on, which is why the handbook treats it as a serious problem rather than a minor one.
Why the other answers are wrong
- B. shiny. — Heat does not make brake parts shiny; the handbook only describes the effect on how well they work.
- C. more efficient. — The handbook says the opposite: overheated brakes are dangerously inefficient, not more efficient.
- D. wet. — Overheating is a heat problem, and the handbook never says it leaves the brakes wet.
Remember it
Think of heat as stealing your stopping power: the hotter the brakes, the less they give you, so let the engine do the work on a long grade.