Two solid yellow lines are painted down the centre of a two-lane road. What do they mean?

Why D is correct

Centre line markings are read like this. A single broken yellow line allows passing when the opposing lane is clear. A solid line paired with a broken one prohibits passing only for traffic running alongside the solid line, so the driver who can see the unbroken mark stays put while the other may overtake when it is safe. Two solid yellow lines forbid it in both directions, and they are painted exactly where visibility fails to support overtaking: crests, curves, and stretches with a history of head-on collisions. Crossing them is not a technical infraction but a decision to meet oncoming traffic you cannot possibly see arriving.

Why the other options are wrong

A. Passing is not allowed from your side of the road only

One solid line next to one broken line is the marking that restricts a single direction. Two solid lines carry no such asymmetry — both directions are bound, which is why they appear where neither side can see far enough to overtake.

B. The lane ahead ends and traffic must merge

Ending lanes are announced by markings that taper, by Merge signs, and frequently by broken lines that guide you across. Nothing about two parallel solid lines suggests a lane is closing.

C. A bicycle lane begins at this point

Bicycle lanes are marked with their own white edge lines, symbols painted on the pavement, and occasionally a solid white buffer. They sit at the road edge, not down the centre.

On the road

A two-lane mountain road climbs toward a blind crest with double yellow all the way. There is rarely another car in sight, which is exactly the temptation. The pair of painted lines is the state telling you it has already measured how far you can see, and the answer is not far enough.

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