Which combination is most suitable for painting fine tree branches over a dry watercolour background?

Correct answer: A fine pointed brush and controlled concentrated paint

The governing concept is controlled detail work on a dry surface, or wet-on-dry application. A fine pointed brush provides a narrow, flexible mark, while moderately concentrated paint keeps the branch visible and prevents uncontrolled spreading. A broad brush, excess water, a wet surface, dripping paint, or clean water alone would produce weak, blurred, or incomplete marks. Therefore, option A is the most suitable combination.