Final answer:
To display the relationship between two sets of data, a bar graph is typically used to compare quantities, whereas a pie chart is ideal for showing the composition of categories as parts of a whole.
Step-by-step explanation:
To illustrate the relationship between two sets of data, you would typically use a bar graph. A bar graph is particularly effective when you want to compare quantities, such as the population sizes of various countries. Each bar in the graph represents a different quantity, making it easy to compare them at a glance. However, if you were looking to show parts of a whole, you might instead use a pie chart. Pie charts are great for displaying qualitative data by showing wedges or slices that represent different categories as proportions of the total.
For instance, if you're showing the composition of different research findings from researchers A and B during an oral presentation, a bar graph would be more desirable to compare the amounts of data or emphasize differences. If, however, you need to represent the percentages of a total for different categories from the research, a pie graph would be appropriate.