You have just driven onto a ramp at a freeway interchange and a large red-and-white sign facing you reads "DO NOT ENTER" above "WRONG WAY". What has happened, and what should you do?

Correct answer: B. You are travelling the wrong way up an exit ramp — stop and get off the ramp before reaching the freeway

You are driving up an exit ramp, against the flow of the freeway. Book 5 says this sign is used "to warn motorists again that they are illegally entering a freeway or highway against the flow of traffic", and that its wording "is intended to strongly alert motorists that they are about to encounter high volumes of high-speed traffic travelling in the opposite direction." It is deliberately angled so that it "is not visible to drivers legally entering the ramp from the freeway" — so if you can read it, it is meant for you. A pavement arrow with a lengthened stem is painted beside it showing the correct direction of travel. Stop, and get off the ramp before you reach the freeway; do not continue and do not try to reason that the sign might be for someone else.

Source: MTO Driver's Handbook: Ontario Traffic Manual, Book 5 — Regulatory Signs (December 2021), Section 9 — DO NOT ENTER / WRONG WAY Sign (Rb-20)