Answer:
Wouldn't be Simple Correct me if I am wrong!
The character Veronica Mars is a student who progresses from high school to college while moonlighting as a private investigator under the tutelage of her detective father. In each episode, Veronica solves a different stand-alone case while working to solve a more complex mystery.
Well a digression is a temporary departure from the main subject in speech or writing. So because the person writing the paragraph getting ill last year has nothing to do with this years cookie sale, I think you are correct, sentence 3 is an example of a digression. So D is the answer.