The bright areas of clouds were completely covered during a wet-on-wet sky wash. How could this have been prevented?

Correct answer: Mark and keep the bright areas less wet

The governing concept is planning and controlling paint flow in a wet-on-wet passage. Before applying the sky wash, the intended cloud highlights should be identified and kept less wet, or left relatively dry, so pigment does not freely spread into them. Option A is correct. Wetting the entire sheet more heavily increases spreading, black destroys the highlights, and oil is incompatible with ordinary watercolour practice.