Answer: D
Correct answer: apply themes, colour schemes and background styles to the presentation
The Design tab controls the appearance of the presentation as a whole: themes, which set a coordinated combination of fonts, colours and effects; variants of each theme; slide size, choosing between 16:9 widescreen and the older 4:3; and Format Background, for fills, gradients and pictures. A theme is more than a look. It defines a palette of named colours - accent 1 through 6, plus text and background - and charts, SmartArt and shapes draw from those names rather than from fixed values, so changing the theme restyles everything consistently. Using theme colours rather than picking arbitrary ones is what makes a deck cohere. Designer, on the same tab, proposes layouts for the content already on a slide. Knowing which tab holds which tool is worth a little effort: Insert holds objects, Transitions and Animations hold motion, Review holds spelling and comments, and View holds the masters.