What is the most controlled way to darken the shadow area of a violet flower?

Correct answer: Add a darker colour in small amounts

The governing concept is gradual value control. To make the shadow of a violet flower darker, a darker colour should be mixed in small increments, with the mixture checked after each addition. This preserves the violet character and prevents an abrupt, muddy result. Option B is correct. A large amount of black may overpower the hue, white makes the value lighter, and yellow shifts violet toward a less pure, warmer mixture rather than simply darkening it.