I would say this character is round (option C) because "his personality, his background, motives and some other features are delineated by the author". He presents a complex personality like real people. It seems that he has different "layers" with contradictory situations and some transformations. However, his personality seems inconsistent. For example, He bits Aileen, then he treats her well because he knows the truth but he ends up killing her dog.
For the first part, distinction's root word would be distinct and the suffix is
-tion.
