The union of the circle and its interior?

Answer 1

The union of a circle and its interior refers to the combination of all points on the circle itself and all points inside the circle. This forms a set that includes both the boundary of the circle and its interior region. In mathematical terms, this union is represented as the circle itself along with all points within the circle, denoted as the closed disk.

Answer 2

This is often also called a "circle", so you may have to infer the specific meaning of "circle" from the context.

Answer 3

It is the disk.