If parallel lines are shown narrowing in the distance, which visual principle do they show?

Linear perspective

Linear perspective is the visual system used to represent depth on a flat surface. In ordinary viewing, parallel edges such as the sides of a road, railway track, or building appear to move closer together as they recede into the distance, even though they remain parallel in reality. Artists represent this effect by directing the lines toward a vanishing point or by making the distant interval appear narrower. Thus option A is correct. Colour mixing concerns combining pigments or light, paper folding concerns manipulating a sheet, and decoration describes appearance without explaining spatial depth. The important clue is the change in apparent spacing and direction with distance; that clue identifies perspective rather than a colour or craft process.

This is a Class 9 Art Education question. Chapter: Elements of Art. Topic: Line.