Zachary Is 16 Years Old, and Has a Lot of Difficulty

Zachary is 16 years old, and has a lot of difficulty with social interactions. He has a hard time understanding the perspective of other people and he often engages in repetitive behaviours that others find very odd. Which of the following disorders best fits Zachary's behaviour?

A) obsessive compulsive disorder
B) autistic disorder
C) borderline personality disorder
D) dissociative identity disorder