Driving along a two-lane highway you pass a narrow wordless triangular sign mounted on the left-hand side and pointing to the right. What does it mark?

Why B is correct

The pennant-shaped no-passing zone marker is one of the few signs whose meaning is carried entirely by shape and placement, with no text at all. It sits on the left-hand side of the road facing the driver and points right, marking exactly where passing stops being legal. Why the left side? Because the driver who needs to see it is the one coming toward it in the lane where overtaking would happen. Nor is it merely a suggestion you can weigh against your own read of the sight distance — it means the agency has already measured that stretch and concluded it is unsafe to overtake. Expect to see it again wherever the road crests or curves.

Why the other options are wrong

A. A hiker crossing ahead

Pedestrian and trail crossings are marked with warning diamonds carrying symbols. A pennant says nothing about people; it reports that forward visibility has been measured and found wanting.

C. A side road joining from the left

Side road warnings use a different shape and sit on the right, near the junction. A pennant on the left shoulder is describing conditions on the road you are already travelling along.

D. A lane ends ahead and you must merge right

Lane-ends and merge signs are placed on the right and usually carry graphics rather than a plain pennant. Nothing here instructs you to change lanes, only whether overtaking is permitted.

On the road

Two drivers crest a hill and begin an overtake at the same moment a third arrives over the crest from the far side. No-passing pennants are posted because someone measured that sight distance and found no driver could judge it safely.

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