Final answer:
The type of shape made up of unpredictable, irregular lines is called an organic shape (option a). Organic shapes contrast with geometric shapes, which are defined by precise and regular lines. Artists use these shapes to convey different emotions and themes in their artwork.
Step-by-step explanation:
The type of shape composed of unpredictable, irregular lines is known as an organic shape. Organic shapes are found within works of art that feature loose, curving lines reminiscent of forms found in nature, expressing a natural and dynamic character.
These include the lines seen in flowing hair, the outline of leaves, or the curves of ruffled clouds. In contrast, geometric shapes have precise and regular lines, such as straight lines or perfect circles, echoing the structured forms found in mathematical geometry. An artwork can have both geometric and organic elements, but the distinction is important as it can reflect different artistic intentions or thematic content.
In the context of line quality, organic lines tend to create a more relaxed and comfortable feeling, often rounded, and have indeterminate paths which contribute to a sense of natural movement within an artwork. These attributes are in contrast to geometric lines, which are associated with a more rigid and controlled visual movement. Accordingly, an artist's use of organic versus geometric lines can greatly affect the aesthetic and feel of a piece.