This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cognitive development and defence mechanism, Subject name: Psychiatry
[{'content': 'Fixation is a concept related to \nSelect and explain. \nA. Psychosocial stages of development, B. Psychosexual stages of development, C. Cognitive stages of development, D. Hierarchy of needs', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fixation is concept introduced by Sigmund Freud, he explains this in his each stage of Psychosexual stages of development. Ref: Synopsis of Psychiatry, 11e, pg 157.', 'role': 'assistant'}]