Which value sequence is suitable for showing the roundness of a raised object in poster colour?

Correct answer: A gradual shift from light through mid-value to shadow

The governing concept is gradual value modelling. On a rounded raised form, light turns progressively across the surface, so the painting should move from the light area through a middle value toward the shadow. The middle value is essential because it connects the light and dark and makes the surface appear curved. An abrupt white-to-black jump looks harsh, one value flattens the form, and an edge alone cannot describe roundness. Therefore B is correct.