Define the term "color wheel" in fashion design.

The term "color wheel" in fashion design refers to a circular diagram that visually represents the relationships between different colors. This tool is essential for designers as it illustrates how colors interact with one another, highlighting complementary, analogous, triadic, and other color schemes. By using the color wheel, fashion designers can create harmonious and visually appealing palettes for their collections, ensuring that the chosen colors work well together in a design. This foundational knowledge helps in making color selections that express the desired mood or theme in their designs, which is crucial in the fashion industry. In contrast, the other options focus on different functions and tools related to fashion design, which do not convey the same concept or importance in understanding color relationships.