This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
An 8 year old child has shown of lack of interest in studies for last 6 months. He has frequent quarrels with his parents and has frequent headaches as anexcuse to avoid school. What would be the most appropriate clinical diagnosis in this patient? 
Select and explain. 
A. Rule out migraine, B. Rule out depression, C. Rule out an oppositional defiant disorder, D. Leave him as normal adolescent problem
C: Rule out an oppositional defiant disorder
Answer: C: Rule out an oppositional defiant disorder 
Explanation: Since the person in the question is showing a hostile behavior which is impairing his academic activities for the last 6 months, the most appropriate next step would be to rule out Oppositional defiant disorder.Oppositional defiant disorder is a recurrent pattern of negativistic, hostile or defiant behavior that lasts longer than 6 months and creates disturbances in at least one of the domains of child functioning including social, academic or occupational impairment. The symptoms of this disorder is usually evident around 6-8 years. Ref: Kaplan and Sadock's Comprehensive Textbook of Psychiatry, 9th Edition, Page 3586, 3580.