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
[{'content': 'A person laughs to a joke, then suddenly loses tone of all muscles. Diagnosis is: DNB 09; JIPMER 13 \nSelect and explain. \nA. Cataplexy, B. Catalepsy, C. Sleep attack, D. Sleep paralysis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Cataplexy', 'role': 'assistant'}]