What does a pie chart represent?

A pie chart is specifically designed to represent parts of a whole. Each slice of the pie corresponds to a category and its proportion relative to the total, allowing viewers to easily visualize how individual segments contribute to the overall data set. The shape and division of the chart provide a clear, immediate indication of how various sections compare in magnitude and importance, making it an effective tool for displaying categorical data.

In contrast, the other options describe different types of visualizations or data representations. For instance, changes over time are typically represented using line graphs, while trends and patterns are best depicted in formats like line graphs or bar charts that allow for a linear or sequential interpretation. Lastly, statistical relationships often require scatter plots or correlation matrices to effectively illustrate how two or more variables interact with each other. Thus, the pie chart's unique focus on portions of a whole is what distinctly defines its purpose and functionality in data visualization.