This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Psychiatry
[{'content': 'Which of the following is not a formal thought disorder? \nSelect and explain. \nA. Delusion, B. Neologism, C. Derailment, D. Tangentiality', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Delusion is a disorder of content of thought. Neologism, derailment, and tangentiality are formal thought disorder.', 'role': 'assistant'}]