Beyond curves and hills, which additional locations require a driver to reduce speed even where no lower limit is posted?

Why B is correct

The rules list specific situations where slowing is required rather than optional, and intersections and grade crossings appear alongside curves, crests and adverse conditions. The logic is identical across all of them: something may enter your path without notice, and the consequence of arriving quickly is not merely a dent. A vehicle entering from a side road, a train that nobody heard, or a pedestrian stepping out all become survivable events if enough speed has been shed beforehand. Signs supplement this duty, and the absence of one never removes it.

Why the other options are wrong

A. School zones during posted hours only

School zones form one item on a longer list rather than the whole of it. Treating them as the only reduced-speed location leaves every crossing and junction unaddressed.

C. Bridges and overpasses with narrow shoulders only

Bridges raise their own concerns about width and surface, but nothing in the reduced-speed duty is confined to them or even mentions them. What the duty names are locations where somebody or something may enter your path unannounced, and a bridge simply does not present that particular problem.

D. None — only curves and hills carry a duty to slow

The list plainly extends past curves and hills. Grade crossings, intersections and narrow roadways appear because they all share the property of concealing what comes next.

On the road

A driver knows this road, knows the crossing carries no signals, and knows nothing has ever come along it. All of that remains true until the afternoon something does, at which point the only variable left is how fast they were going.

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