Brittni uses semi-precious gemstones, beads, clasps, and cord to make one-of-a-kind Southwestern-inspired jewelry. What type of utility does Brittni create?

It creates Form.

A Form is a shape that is combined like together. So, in this case "one-of-a-kind Southwestern-inspired jewelry" would create form. A better way to describe Form utility is having a product and making it better. For example, in this case we have Jewelry - let's say we add extra designs. That would make form.