Which feature adds to a sketch by using outlines from an existing sketch?

The correct choice, which adds to a sketch by utilizing outlines from an existing sketch, is the "Project" feature. This function enables users to project geometrical elements from an existing sketch onto a new sketch plane. By using this tool, you can establish relationships between the new sketch and the original elements, ensuring that any modifications in the original outline can automatically adjust the new sketch as needed. This capability is essential for maintaining design consistency and facilitating efficient modeling workflows, especially in complex designs where sketches need to align with existing features.

In contrast, the other options serve different purposes: "Revolve" is used for creating 3D objects by rotating a 2D sketch around an axis, "Rigid Group" allows for the selection of multiple sketch entities to move and behave as a single unit without affecting their relative positions, and "Section View" is a method of visualizing internal features of 3D models by cutting through them, which does not involve adding to sketches directly.