Why should the palette be clean during secondary colour mixing practice?

Correct answer: To obtain clean and intended colour mixtures

A clean palette prevents leftover paint from entering a new mixture. For example, red and yellow should produce a clear orange, but traces of blue or another colour can reduce its brightness and alter its hue. Cleaning the palette therefore helps the learner obtain the intended secondary colour accurately. It does not make colours heavier, dry paper, or harden brush bristles. Option B is correct because palette cleanliness protects colour purity and makes the result easier to judge.