The correct answer is A. Slide sorter view.
In slide sorter view, you can see all of the slides in your presentation at once. This makes it easy to see how the slides will flow together and to set transition effects for all of the slides.
B. Notes pages view shows the slide and the speaker notes for that slide. This view is useful for creating notes to accompany your presentation, but it is not the best view for setting transition effects.
C. Slide view shows a single slide in full screen. This view is useful for editing the content of a slide, but it is not the best view for setting transition effects.
D. Outline view shows the outline of your presentation, without the actual slides. This view is useful for planning your presentation, but it is not the best view for setting transition effects.