What is the correct way to correct a small wet paint spill outside a boundary?

Correct answer: Gently lift it with a clean damp brush or tissue

The governing technique is gentle correction while the paint is still wet. A clean, slightly damp brush or tissue can lift excess colour by blotting, allowing the boundary to be restored without spreading the mark. Therefore, option A is correct. Spreading the paint enlarges the error, black paint may create a harsh patch, and hard rubbing can damage the paper surface.