Your Little Brother Constantly Disobeys Your Parents, Talks Back to Them

Your little brother constantly disobeys your parents, talks back to them, and refuses to acknowledge what they say. What DSM-IV-TR category would fit his symptoms?

A) Oppositional Defiant Disorder
B) Separation Anxiety Disorder
C) Disorders usually First Diagnosed in Infancy, Childhood, and Adolescence
D) Adjustment Disorders
E) Conduct Disorder