A school bus has finished dropping off its last passenger, but one child still has to cross the road in front of the bus. When is the bus driver allowed to switch the red lights and stop arm off?

Correct answer: B. Only once every passenger who has to cross the road has completed the crossing

Not until that child is across. HTA s.175(6)(c) requires a school bus driver, while stopped to receive or discharge passengers, to "continue to operate the overhead signal-lights and stop arm until the passengers have been received or discharged **and until all passengers having to cross the highway have completed the crossing**." Two conditions, and the crossing one usually outlasts the other. This is why the corresponding duty on you runs until the bus moves or the lights stop flashing rather than until the doors close: the lights are still on precisely because someone is still in the road. A bus that has shut its doors but kept its lights flashing is telling you that a child is crossing in front of it, out of your view.

Source: MTO Driver's Handbook: HTA Section 175(6)(c) — how long the bus driver keeps the lights and stop arm going