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 who laughs one minute and cries the next without any clear stimulus is said to have - \nSelect and explain. \nA. Incongruent effect, B. Euphoria, C. Labile affect, D. Split personality', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Lability (labile affect)\n\nSudden and short - lived changes in emotional response, i.e. emotional changes are very rapid, e.g. from sorrow to joy.', 'role': 'assistant'}]