Which can be the most effective method of creating a focal point in a monochromatic composition?

Correct answer: Create strong differences in value, size, or texture

The governing concept is emphasis within a monochromatic scheme. Because the hue is restricted to one colour family, the artist can create a focal point by changing value from light to dark, varying scale, or introducing a noticeable texture difference. Thus option C is correct. Keeping all values equal removes contrast, changing hue only is limited in a monochromatic work, and removing colour does not by itself create emphasis.