Final answer:
The design line used to build a weight area in a graduated form is the diagonal orientation or diagonal weight distribution.
Step-by-step explanation:
The design line that is used to build a weight area in a graduated form is called the diagonal orientation or diagonal weight distribution. This design technique creates a visual sense of movement and balance by placing the weight at an angle rather than simply resting it at the top or bottom of the composition. By using diagonal lines or shapes, the weight area can be distributed in a way that is visually interesting and dynamic.