Final answer:
A non-linear plot diagram in literature typically includes subplots, flashbacks, and foreshadowing.
Step-by-step explanation:
A non-linear plot diagram in literature is characterized by subplots, flashbacks, and foreshadowing. Subplots are secondary storylines that run parallel to the main plot and involve supporting characters. Flashbacks are scenes that interrupt the chronological order of the narrative to show events from the past. Foreshadowing is a literary technique where hints or clues are given about future events in the story. Therefore, the correct answer is D.) all of the above.