California Assessment of Student Performance and Progress (CAASPP) Math Practice Exam 2026 - Free CAASPP Math Practice Questions and Study Guide

A figure is classified as a polygon if it is a closed plane figure made up of a finite number of straight line segments. Therefore, each side of the polygon must indeed be a line segment, which is a fundamental condition for the definition of a polygon. This means that all sides must connect in such a way that they form a closed shape without any curves or gaps.

The other options fail to meet the requirements for a polygon. For example, if a figure has curved edges, it cannot be classified as a polygon. Similarly, being three-dimensional is not a requirement; polygons exist in two-dimensional space. Lastly, while polygons can have various angles, there is no requirement for them to have an equal number of angles; the number of angles corresponds to the number of sides, but they do not have to be equal. Hence, the necessity for each side to be a line segment is the correct condition for classification as a polygon.