How can harmony be preserved while maintaining variety in a monochromatic composition?

Correct answer: Through controlled changes in value, texture, and shape within one colour

A monochromatic composition is unified by using one colour family, including its tints, tones, and shades. Variety can still be introduced through controlled changes in lightness, texture, edge, and shape without abandoning that family. Option C therefore preserves unity while adding visual interest. Adding unrelated colour families weakens the scheme, identical values create monotony, and removing all texture unnecessarily reduces expressive possibilities.