Concept:A presentation design template gives all slides a consistent look and feel.
Explanation:To make every slide in a PowerPoint presentation share the same appearance, you need a unified design source.
A design template contains matching backgrounds, colours, fonts, and layouts.
When applied, it automatically updates each slide to use that same visual style.
Changing the view to slide show only affects how you display the presentation.
Adding another slide option only inserts a blank or duplicate slide.
Formatting the slide layout adjusts a single slide’s arrangement, not the whole presentation.
Therefore, the correct action is to add a presentation design template.
This ensures every slide has the same look.
Answer:D. Add a presentation design template