What may happen if the brush carries too much paint while filling?

Correct answer: Paint may drip and cross the boundary

The governing concept is controlling the paint load for accurate filling. When a brush carries too much paint, the excess reduces precision, may form a heavy wet spot, and can drip beyond the intended outline. Thus option D is correct. Paint does not disappear, paper does not shrink, and the brush does not become lighter merely because it contains excess colour.