Which type of graph is most effective for displaying the relationship between two quantitative variables in a clear and visually understandable manner?

The most effective graph for displaying the relationship between two quantitative variables is a scatter plot. A scatter plot shows individual data points on a two-dimensional grid, with one variable on the x-axis and the other on the y-axis. This allows you to see how the two variables relate to each other, such as whether they increase together or if one affects the other. For example, if you were looking at the relationship between hours studied and test scores, a scatter plot would let you see if students who study more tend to score higher. This visual representation makes it easier to identify patterns or trends in the data.