When another vehicle is merging into your lane from the right, you should
- move over into the oncoming traffic lane.
- speed up.
- sound your horn to warn the other driver to yield.
- slow down and let it merge. ✓
Answer: D. slow down and let it merge.
Slow down and let the merging vehicle join your lane.
Why this is the answer
The handbook describes the merge sign as marking two roads going the same direction that are about to become one, and it says drivers on both roads share equal responsibility for making that merge smooth and safe. A driver already in the lane can hold up their end of that by easing off the speed and leaving a gap, rather than forcing the merging vehicle to fight for space. Nothing in the passage gives the through driver the right to close the gap or to demand that the other driver yield.
Why the other answers are wrong
- A. move over into the oncoming traffic lane. — Moving into the oncoming traffic lane puts you head-on into traffic coming the other way, and the handbook's merge guidance is about joining lanes going the same direction, not crossing into opposing ones.
- B. speed up. — Speeding up shrinks the space the merging vehicle needs and works against the shared responsibility the handbook describes for making the merge smooth and safe.
- C. sound your horn to warn the other driver to yield. — The passages never tell you to sound the horn here, and honking does not create the gap the merging driver needs to enter safely.
Remember it
Think of a merge as a zipper: the vehicle already in the lane eases off so the two rows slot together instead of colliding.
Official handbook: Official MTO Truck Handbook, Signs – Warning signs