Speed, distance, and safety margins
Stopping distance has two parts
Stopping distance is reaction distance (before braking) plus braking distance (after braking begins).
What to watch for
The question asks about reaction time, braking distance, or total stopping distance.
The rule
The rule explains exactly how to answer any question of this type — and why the obvious wrong answer fails.
See the rule →Common trap
Don't think braking starts the moment you see a hazard.