Final answer:
To edit the cell range reference for the Research category in the Marketing Budget Plan worksheet, only include the Research types under the heading.
Step-by-step explanation:
In the Marketing Budget Plan worksheet, you need to edit the cell range reference for the Research category. Specifically, you should only include the Research types listed under the heading. To do this, you can modify the formula or function in the cell that references the Research category. By specifying the range of cells that contain the Research types under the heading, you ensure that only those specific cells are included in the calculation or analysis.