Final answer:
The Excel option that should be modified to ensure function results are not automatically calculated until a workbook is saved is Activate Manual Calculation Mode.
Step-by-step explanation:
The Excel option that should be modified to ensure function results are not automatically calculated until a workbook is saved is d) Activate Manual Calculation Mode.
When manual calculation mode is activated, Excel will not automatically calculate the functions and formulas in a workbook until you specifically instruct it to do so. This can be useful when working with large datasets or complex formulas, as it prevents unnecessary recalculations. To activate manual calculation mode, go to the Formulas tab, click on the Calculation Options button, and select Manual.
By using manual calculation mode, you have more control over when the calculations take place, helping to optimize the performance of your workbook.