Why are vertical lines useful while showing a building or a tree?

They make height and uprightness clear

Vertical lines run upward and downward, so they naturally suggest height, standing position, support, and stability. This makes them useful when drawing structures or living forms that rise from the ground. The sides and pillars of a building can be shown with vertical lines, while the trunk of a tree and many of its upright branches can also be represented in this way. The effect is visual: the direction of the lines helps viewers read the form as tall and upright.

Therefore option A is correct: vertical lines make height and uprightness clear. They do not always make an object round, because roundness is better suggested by curved lines. They do not erase colours, and they do not make distance impossible. Although perspective may change the appearance of lines in a drawing, their basic expressive association with height and standing remains useful in art.

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