If the upper part is very heavy how can composition feel?

Unstable and top-heavy

The governing concept is balance, especially the distribution of visual weight within a composition. Visual weight is the amount of attention or apparent heaviness created by an object through its size, position, colour, contrast, density, or detail. When a large, dark, or detailed area is placed high in the composition without a counterweight below or elsewhere, the eye may feel that the arrangement is tipping or lacking support. Thus the composition can feel unstable and top-heavy, making option A correct. It does not necessarily become very light, perfectly symmetrical, or colourless. A skilful artist may deliberately create this imbalance to suggest tension, danger, or movement, but the immediate visual effect described by the question remains top-heaviness and instability.

This is a Class 10 Art Education question. Chapter: Fundamentals of Visual Arts. Topic: Balance.