You are on a freeway entrance ramp and, unusually, there is a YIELD sign at the end of it. What should you read into that?

Correct answer: A. The acceleration lane is shorter than the standard for that road's speed, so you have less room to merge

That you will not get the usual run-up. Book 5 says a YIELD sign should be considered "on an entrance ramp to a freeway or expressway, where the acceleration lane or taper is less than specified" in its table — and its own rule is that yield signs are not used "on entrance ramps that are designed to, or exceed, standards." So the sign is there precisely because the merging lane is shorter than it should be for the speed of the through road. Practically, that means less room to match speed and more need to pick your gap before you commit. The same reasoning puts YIELD signs on channelized right-turn lanes with short acceleration lanes. What the sign requires is unchanged: yield to traffic on the road you are joining, stopping if necessary.

Source: MTO Driver's Handbook: Ontario Traffic Manual, Book 5 — Regulatory Signs (December 2021), Section 3 — YIELD RIGHT-OF-WAY Signs, Guidelines for Use