You can show the shortcut menu during the slide show by

To show the shortcut menu during a slide show in PowerPoint, you should use Option B: Right clicking the current slide. This action brings up the shortcut menu where you can access various options and commands.
Option A: Clicking the shortcut button on the formatting toolbar is incorrect because there isn't typically a dedicated "shortcut button" on the formatting toolbar specifically for showing a shortcut menu during a slide show.
Option C: Clicking an icon on the current slide is not a standard method for showing a shortcut menu during a slide show.
Option D: A and B is incorrect because Option A does not describe a valid method for showing the shortcut menu during a slide show.
Therefore, the correct answer in this context is Option B: Right clicking the current slide.