Which activity is most suitable for beginning watercolour practice?

Correct answer: Create a light-to-dark wash of one colour

A light-to-dark wash using one colour is an effective beginner exercise because it develops control over water, pigment concentration, brush movement, and gradual value change. Therefore option A is correct. A complex painting introduces too many skills at once, mixing all colours usually creates a dull muddy result, and covering the paper in black does not practise controlled tonal transitions.