What type of graph is used when comparing the relative proportions or percentages of several subgroups within a single category?

A pie chart is specifically designed to show the relative proportions or percentages of various subgroups within a single category. Each slice of the pie represents a different subgroup, illustrating how each part contributes to the whole. This visual representation makes it easy for viewers to quickly grasp the differences in size or importance among the subgroups, as the size of each slice corresponds to its proportion of the total.

In contrast, the other types of graphs serve different purposes. A bar graph is better suited for comparing categories across discrete values rather than depicting parts of a whole. A line graph shows trends over time with continuous data points connected by lines, and a scatter plot is used to display the relationship between two quantitative variables, making them unsuitable for conveying part-to-whole relationships as effectively as a pie chart.