Concept:Settlements are classified by their shape and layout.
Explanation:When houses are built in a long row along roads, rivers, or railway lines, the settlement takes the form of a line.
This pattern is known as a linear settlement.
It is different from scattered or dispersed settlements, where houses are spread out with no clear line.
Rural settlements simply refer to villages in the countryside, not a particular shape.
Therefore, the correct description of houses built along routes is a linear settlement.
Answer:Linear settlements (Option C).