While applying a wash with a mop brush light dry patches appear in the middle. What is the most likely cause?

Correct answer: The brush was not continuously loaded with enough mixture

The governing concept in a wash is maintaining an even film of diluted colour and moisture across the working area. If a mop brush is not reloaded with enough prepared mixture, its moisture and pigment run out during the stroke, so the middle becomes pale or dry. Paper whiteness, the colour’s name, and handle length do not cause this specific interruption. Continuous loading and a well-mixed supply prevent it, making option B correct.