The correct answer is A. File, add a new slide.
To add a slide to an existing presentation, you can use the “Insert” tab on the ribbon. In the “Slides” group, click the “New Slide” button. You can then choose from a variety of slide layouts.
The “File” menu contains commands for managing your presentation, such as opening, saving, and printing. The “Open” command allows you to open an existing presentation. The “New” command allows you to create a new presentation.
I hope this helps!