What is a requirement when constructing a scattergram?

A scattergram, also known as a scatter plot, is specifically designed to visualize the relationship between two quantitative variables. When creating a scattergram, the requirement is that it illustrates how one variable changes in relation to another, allowing researchers to identify patterns, trends, and potential correlations between the two. This graphical representation is particularly useful for observing the nature of the relationship—whether it is positive, negative, or non-existent.

Including multiple datasets is not a requirement for a scattergram; it typically focuses on two variables at a time. Examining only independent variables is also not relevant, as a scattergram can display both independent and dependent variables, depending on the research question. Lastly, scattergrams are not appropriate for categorical data, as they are meant for continuous data to accurately reflect variations and relationships. Thus, the necessity of depicting relationships among two variables makes the given answer correct.