Approaching a railway crossing that has gates or signal lights, you notice a large white "X" painted on the pavement of your lane, well before the tracks themselves. What is this pavement marking for?

Correct answer: C. It's a required pavement-marking warning of the railway crossing ahead, used alongside signs and signals, not instead of them

At railway crossings with grade crossing signals or automatic gates — and at any crossing where highway traffic speed is 60 km/h or greater — the Ontario Traffic Manual requires a large white "X" (2.5 m wide, 6 m long) painted in each approach lane as part of the pavement-marking warning system, positioned in advance of the crossing itself. It works together with, not instead of, the advance warning sign and other devices — pavement markings alone are never treated as sufficient warning on their own.

Source: MTO Driver's Handbook: Ontario Traffic Manual, Book 11 — Pavement, Hazard and Delineation Markings, Railways — Crossing Approaches