Approaching a level crossing that sits just before a busy intersection, you see a regulatory sign with a red interdictory ring meaning "do not stop on tracks". Traffic ahead is backed up past the crossing. What should you do?

Correct answer: B. Wait behind the tracks until there is space for your whole vehicle on the far side

Stay behind the crossing until there is room for your whole car on the far side. Book 5 says the DO NOT STOP ON TRACKS sign "indicates that stopping is prohibited at all times on all days, on the railway tracks," and that it is installed "where there is a recognized problem of vehicles stopping on the tracks, such as during rush hour and when the level crossing is located near an intersection." The sign exists because of exactly the situation you are in: a queue that looks like it is moving swallows the space you were counting on, and the car that follows the traffic ahead too closely ends up stationary between the rails with a gate coming down. This is the same instinct the Driver's Handbook asks for at any crossing — make sure you have room to cross completely before you begin.

Source: MTO Driver's Handbook: Ontario Traffic Manual, Book 5 — Regulatory Signs (December 2021), DO NOT STOP ON TRACKS Sign (Rb-113)