Final answer:
A scatter plot is the most effective graph to compare the association between two quantitative variables, revealing trends and potential correlations through the proximity of data points.
Step-by-step explanation:
The best type of plot to compare the association between two quantitative variables is a scatter plot. A scatter plot allows individuals to visualize the relationship between two sets of data. Each point on the plot represents a pair of values, with one variable on the x-axis and the other on the y-axis. When points are close to each other, it suggests a strong relationship, whereas points that are more spread out indicate a weaker relationship. It's very helpful for identifying trends, patterns, and potential correlations between variables.
Other plots like bar plots, line plots, and pie charts serve different purposes. A bar plot is used to compare different groups; a line plot is ideal for illustrating the change of one variable over time or another continuous variable; and a pie chart represents how different parts make up a whole. However, they are not as effective in showing the direct association between two quantitative variables as a scatter plot is.