Answer: A
Correct answer: Slide timings, transitions, animations and any recorded narration
Exporting to video preserves the presentation as it plays: slide timings, transitions, animations, media and any recorded narration or pointer movements. The point of it is distribution to viewers who may not have PowerPoint, or who will watch without a presenter - a recorded lecture, a conference submission, a video shared online. Timings must exist for the video to advance. Either they are set through Rehearse Timings or Record Slide Show, or a default number of seconds per slide is specified in the export dialogue. The export offers a choice of resolution, and a higher one gives a larger file; export can take some minutes for a long deck, and it runs in the background. What is lost is editability - the fourth option - since the result is a video file. The original .pptx must be kept if the presentation will ever need changing. The alternative export is to PDF, which preserves the slides as static pages.