You are approaching a signal that has been green the entire time you have been able to see it. What is the defensive habit for this situation?

Why A is correct

A green light you did not see turn green is a stale green: its age is unknown, and signals do not announce how much phase remains. The defensive habit is to cover the brake as you approach, keep your speed settled, and be genuinely ready to stop when the yellow appears — because it will appear, and your readiness decides whether the change is a smooth stop or a hard one. It pairs with checking your mirror as you approach, so that if you do brake, the driver behind has a braking you rather than a surprise.

Why the other options are wrong

B. Accelerate to cross before the signal phase changes

Racing a light of unknown age is betting on a timer you cannot see. The stale green is precisely the display most likely to change while you are under it, and speed makes every outcome of that change worse.

C. Sound the horn and proceed at constant speed

The horn communicates nothing useful to a signal and adds noise for everyone else. A stale green is handled with quiet readiness — foot over the brake, eyes on the junction, decision already half-made.

D. Ignore the signal and rely on cross traffic to obey their red

Cross traffic obeying their red is not information you control; it is information you hope for. The habit of covering the brake exists because the one thing you can guarantee is your own readiness, not other people's compliance.

On the road

Coming up a gentle rise toward the junction on your commute, the light has been green since it cleared the skyline. You settle off the throttle and hover the boot over the pedal. Halfway through the block it flips to yellow, and you stop on a comfortable, early brake — while the car behind you, driver mid-phone, stops two lengths later than they would have if you had been panic-braking at the line.

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