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
The primary disturbance in schizophrenia is 
Select and explain. 
A. Hallucination, B. Illusion, C. Psychomotor Retardation, D. Formal Thought Disorder
D: Formal Thought Disorder
Answer: D: Formal Thought Disorder 
Explanation: D i.e. Formal thought disorder