The correct answer is A. Design templates.
A design template is a pre-made set of formatting and layout options that can be used to create a presentation. It includes the slide master, which contains the design elements for the entire presentation, as well as the slide layouts, which contain the placeholders for text, images, and other objects.
A template is a general term for a pre-made document that can be used as a starting point for creating a new document. It can include formatting, layout, and content.
A placeholder is a specific location on a slide where text, images, or other objects can be inserted.
A blueprint is a detailed plan or drawing of a building or other structure.
In conclusion, design templates are the most common type of template used for presentations. They provide a consistent look and feel for all of the slides in a presentation, and they can save time and effort when creating a new presentation.