Answer : 1. "F5"
Explanation :

1. The shortcut key to start the slide show from the beginning in MS PowerPoint is F5. Pressing this key will start the presentation and slide show starting from the first slide.

2. If you want to start the slideshow from the current slide, you can use the Shift+F5 key combination. Pressing this key will start the presentation and start the slide show from the current slide.