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
A person who laughs one minute and cries the next without any clear stimulus is said to have - 
Select and explain. 
A. Incongruent effect, B. Euphoria, C. Labile affect, D. Split personality
C: Labile affect
Answer: C: Labile affect 
Explanation: Lability (labile affect)

Sudden and short - lived changes in emotional response, i.e. emotional changes are very rapid, e.g. from sorrow to joy.