What should be done to avoid unwanted water spots in a watercolour painting?

Correct answer: Brush and paper moisture should be controlled

The governing technique is moisture control. Too much water on the brush, paper, or painted area can spread pigment unpredictably and leave blooms or unwanted spots as the wash dries. The artist should use an appropriate water-to-pigment ratio, remove excess water from the brush, and avoid disturbing partly dry areas. Oil, repeated folding, and adding black do not solve the problem. Thus, option A is correct.