The boundary between two blended colours appears too hard. What should be done?

Correct answer: The boundary should be gently blended with a clean, slightly damp brush

The governing concept is soft-edge blending between adjacent colours. A clean brush with only slight moisture can gently work across the meeting area, allowing the two colours to transition without creating a new mark. Option B is correct. A black line would make the boundary harder, complete drying would fix the edge instead of softening it, and dry powder is not a controlled blending method. Excess water should be avoided because it can cause blooms or unwanted spreading.