Which feature is used to define a specific profile in Fusion 360?

Creating a sketch is fundamental in defining a specific profile in Fusion 360. A sketch serves as a 2D representation that can be used to generate 3D models. Within a sketch, you can draw geometric shapes, apply constraints, and dimension elements, which establish the exact outline or profile you want to work with in your design. Once the sketch is complete, it can be extruded, revolved, or used in other operations to create three-dimensional components.

The other options do not directly relate to defining a profile. Model design is a broader term that encompasses various design processes but does not specifically refer to creating profiles. The material library is used for assigning physical properties and appearance to designs, not for drawing profiles. Simulation setup pertains to preparing models for testing their performance under various conditions, which is not involved in defining the initial contours or outlines of a profile.