Which option shows the correct transition in form shading?

A gradual change from light to shadow on a curved form

The governing concept is tonal gradation: a curved form appears rounded when its values change progressively according to the direction of light. On a sphere or cylinder, the highlight moves through middle tones toward the core shadow, and the transition is generally smooth rather than broken into unrelated patches. Therefore, option A is correct because gradual light-to-shadow change communicates turning surface, volume, and depth. Option B produces a flat, artificial appearance; option C removes the value information needed to describe volume; and option D omits the very light-dark relationship that makes a cylinder readable as a solid form. The exact softness may vary with the material, but the basic principle remains gradual value change.

This is a Class 9 Art Education question. Chapter: Elements of Art. Topic: Form.