Final answer:
To reset the ribbon to its default settings, the reset button in the Customize dialog box should be clicked, which can be found in the options for Microsoft Office applications.
Step-by-step explanation:
You can reset the ribbon to its installation default by clicking the reset button in the customize the ribbon options in the Customize dialog box. The correct answer is d) Customize. This can typically be accessed in Office applications like Microsoft Word, Excel, and PowerPoint by right-clicking on the ribbon and selecting 'Customize the Ribbon...' or by going to File > Options > Customize Ribbon. In the dialog box that appears, you will find a button or link to reset the ribbon. When you click this, it will reset the layout and tabs of the ribbon to the default settings that were originally installed with the application.