Why are clean vertical and horizontal lines necessary in an architectural drawing?

They clarify structural stability and correct proportion

Architectural drawing depends on accuracy, measured relationships, and a clear representation of built structure. Vertical lines help communicate upright walls, columns, and the sense that a building is standing securely. Horizontal lines can indicate floors, edges, ground levels, roofs, and other structural alignments. When these lines are clean and correctly placed, proportions and relationships among parts are easier to judge. Option A is correct because it connects line quality and direction with structural stability and proportion. Option B is unrelated to architectural accuracy, C is false because straight reference lines do not make every object round, and D describes neither their purpose nor their visual function. The governing concept is that controlled line direction provides order and measurable structure in technical and architectural representation. Perspective may alter apparent convergence, but precision remains essential.

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