It is most important to flash your brake light when
- someone is following you too closely.
- there is a stop sign ahead.
- you will be slowing suddenly. ✓
- your signals are not working.
Answer: C. you will be slowing suddenly.
It is most important to flash your brake light when you will be slowing suddenly.
Why this is the answer
The handbook says your brake light tells traffic behind that you are slowing, and you should flash it before you slow down. It lists sudden slowing as one of the times this matters especially. A gentle tap on the front brake lever or rear brake pedal makes the light flash without actually braking. That warning gives drivers behind a chance to notice what you are about to do; the handbook does not single out stop signs or broken signals for this.
Why the other answers are wrong
- A. someone is following you too closely. — Flashing when someone follows closely can help, but the handbook treats that as general communication rather than the most important time, which is before you slow down suddenly.
- B. there is a stop sign ahead. — A stop sign ahead is not given as a reason to flash the brake light; the passages talk about warning before slowing, not about announcing signs.
- D. your signals are not working. — The passages do not say to flash the brake light because your signals are not working; they describe it as a warning that you are slowing.
Remember it
Think tap first, slow second: a light brake-lever tap warns the traffic behind.
Official handbook: ICBC Learn to Ride Smart, Chapter 6: see-think-do – do, p. 87