Final answer:
A quadrilateral that has four equal sides and four equal angles is classified as a regular quadrilateral.
Step-by-step explanation:
The type of polygon that is classified by the number of sides as equilateral, equiangular, or regular is a Quadrilateral; regular. Quadrilaterals are polygons with four sides, and if all four sides are equal in length and all four angles are equal, it is considered a regular quadrilateral. Examples of regular quadrilaterals include squares and rectangles. A regular polygon is both equilateral and equiangular; the only option that indicates a polygon that is regular is option C) Octagon; regular, meaning all sides and angles of the octagon are equal.