What is the primary purpose of a scatterplot?

A scatterplot is specifically designed to illustrate the relationship between two quantitative variables. By plotting points on a two-dimensional graph, where each axis represents one of the variables, a scatterplot allows researchers to visualize trends, correlations, and potential relationships between the variables being studied.

For instance, if you were examining the relationship between study hours and exam scores, each point on the scatterplot would represent a participant's study hours (on the x-axis) and their corresponding exam score (on the y-axis). This visual representation can help identify patterns, such as whether more study hours tend to correlate with higher exam scores.

While other options address important aspects of data visualization, they do not pertain to the function of a scatterplot. Categorical variables or distributions of a single variable would require different graphical representations, like bar charts or histograms, respectively. Additionally, comparing multiple variables at once usually involves more complex visualizations, such as multiple scatterplots or other multi-dimensional data representations. Thus, the primary purpose of a scatterplot remains to represent the relationship between two quantitative variables effectively.