This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neurotic, Stress Related and Somatoform Disorders, Subject name: Psychiatry
[{'content': "A 19-year-old man working as a driver comes to Psychiatrist with excessive anxiety and fear. He repos that every time he drives over a bump in the road, he is convinced that he has accidentally run over a small child. He has to pull over and check underneath his car for blood and retrace his driving route to look for any injured children. As a result, he is always late for work.He also has intrusive thoughts about stabbing his coworkers.He prays to try to erase these thoughts from his mind, but this rarely helps. First-line pharmacological treatment of this patient's condition primarily affects which of the following neurotransmitters? \nSelect and explain. \nA. Acetylcholine, B. Dopamine, C. Norepinephrine, D. Serotonin", 'role': 'user'}, {'content': "Answer: D \nExplanation: Patient's behavior is suggestive of Obsessive Compulsive Disorder. Although multiple neurotransmitters and regulatory mechanisms are thought to contribute to the clinical expression of OCD ,serotonin is the primary pharmacological target. First-line treatment is a selective serotonin reuptake inhibitor(SSRI) antidepressant.", 'role': 'assistant'}]