One of your two headlights has burned out. The other works fine and the road you take home is well lit. Is it acceptable to keep driving until the weekend?

Correct answer: B. No — replace the bulb as soon as possible; one headlight reads as a motorcycle to oncoming drivers

No. The Handbook is direct: "Don't drive with only one headlight or with lights that are not aimed properly. Have your full lighting system checked regularly, keep them clean, and replace burned-out bulbs as soon as possible." A single working headlight does more than halve your light — from a distance it reads as a motorcycle, so an oncoming driver misjudges both what you are and how wide you are. The same section sets out what your lights are supposed to achieve: a white light visible at least 150 metres ahead and strong enough to light up objects 110 metres away, red rear lights visible from 150 metres, and a white light on the rear licence plate whenever the headlights are on. A burned-out bulb or a misaimed beam quietly fails that standard.

Source: MTO Driver's Handbook: Getting ready to drive — Turn on headlights at night and in poor conditions, burned-out and misaimed lights