This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Schizophrenia Spectrum and Other Psychotic Disorders, Subject name: Psychiatry
A 40-year-old woman is brought by her husband for complaint of abnormal behavior. During the interview, she laughs and cries with a very sho period of time spontaneously. Her affect is best described as? 
Select and explain. 
A. Apathy, B. Blunted affect, C. Euthymic affect, D. Labile affect
D: Labile affect
Answer: D: Labile affect 
Explanation: Labile affect Labile mood Sudden alterations in emotional responses, not related to environmental events Alternates between euphoric and dysphoric moods Apathy: Lack of concern Blunted affect: Greatly decreased display of emotional responses Euthymic: Normal mood, with no significant depression or elevation of mood