At the rear of a bus, you see a rectangular yellow plate with a red border, or two equivalent plates placed symmetrically. What does that marking indicate?

That it is a regular-route bus.

At the rear of a bus, you see a rectangular yellow plate with a red…

Correct answer

That the bus is more than 12 metres long.

The vehicle or combination is over 12 metres long. It is the V-6 long-vehicle marking. A single plate may be centred at the rear or, where advisable, two equivalent plates positioned symmetrically near the edges. It does not by itself identify an articulated bus or a regular-route service. The question describes the marking, so identifying it does not depend on a photograph.