As for this problem, the most probable and the most likely answer to this would be D. At the end of the presentation. This would be in regards to taking into consideration the presented options together with the problem.
When a summary slide is inserted into a presentation, it appears at the end of the presentation. As a summary slide, it would serve its purpose either at the beginning of the presentation or at the end of the presentation. Updates has allowed users to place a summary slide anywhere they please, but the default place would be at the end of the presentation.