Apart from hills and curves where you simply cannot see far enough, where else should you expect to find a solid yellow no-passing line on a two-lane road?

Correct answer: C. Approaching an intersection, approaching an obstruction you must pass on the right, at lane reductions, and in school zones

At several places that have nothing to do with sight distance. Book 11 lists where a no-passing zone may be established: "where passing would be hazardous (for example, where sight distance is restricted by vertical and/or horizontal curves, at the approach to an intersection, at the approach to an obstruction that must be passed on the right, at lane reduction or transition areas, or in a school zone)." So an approach to an intersection, an approach to an island or obstruction you must go around on the right, a place where the road narrows, and a school zone all attract the same solid line as a blind crest does. The marking itself is standard: "a no-passing zone must be marked with a barrier line in addition to a directional dividing line."

Source: MTO Driver's Handbook: Ontario Traffic Manual, Book 11 — Pavement, Hazard and Delineation Markings (March 2000), Section 3.7 — Barrier Lines, no-passing zone criteria