Answer: B
Correct answer: group slides into named blocks that can be collapsed and moved together
Sections group slides into named blocks. A section can be collapsed to a single heading, expanded again, moved as a unit, or removed with all its slides. They are added by right-clicking between two slides in the thumbnail pane or in Slide Sorter view and choosing Add Section. Their value grows with the length of a deck. A presentation of eighty slides is unmanageable as a flat list; divided into six named sections it can be reordered wholesale, and collapsing the sections not being worked on makes navigation immediate. They also help when several people contribute, since each can own a section. Sections appear in Presenter View, so a speaker can jump to a named part rather than hunting by thumbnail. They are purely organisational and have no effect on the presentation as the audience sees it - unlike Hide Slide, which changes what is shown, or a Custom Show, which defines a subset of slides to present.