How should the difference between two adjacent boxes in a value scale appear?

Correct answer: Gradual and clear

The governing concept of a value scale is an organised progression from light to dark. Adjacent boxes should change by a noticeable but controlled amount, producing gradual and clear steps rather than a sudden jump. Hence option B is correct. A large abrupt change breaks the scale, no change removes the progression, and colour alone is not required in a pencil value scale.