What may generally happen when red, yellow, and blue pigments are mixed in substantial amounts?

Correct answer: A muddy or dark neutral colour may form

The governing concept is subtractive pigment mixing. Each pigment absorbs part of the available light; combining red, yellow, and blue over substantial amounts increases broad absorption and usually produces a dull, muddy, dark neutral colour rather than a bright one. Therefore option A is correct. White is associated with additive light mixing, green needs mainly yellow and blue, and orange comes primarily from red and yellow.