Final answer:
Explanatory text on a graph should be placed outside the plot area to ensure clarity and readability, allowing the graphical data to remain unobstructed.
Step-by-step explanation:
When adding explanatory text to a graph, it is generally best practice to place it outside the plot area. This helps to ensure that the text does not obstruct the data or elements within the graph, such as the data points, lines, or bars. Explanatory text can include titles, labels for the axes, a legend, or additional notes that provide context to the graph. Placing this text outside of the plot area contributes to a clear and readable graph that communicates information effectively.