Which of the following is the least likely outcome when a monopoly adopts perfect price discrimination because of the customers’ differing demand elasticities（）

A. The monopolist shares the total surplus with consumers.

B. The price for marginal unit is less than the price for other units.

C. The output increases to the point at which price equals the marginal cost.

中年男性，反复气短20余年，近2年常有胸骨后疼痛，胸骨右缘第2肋间3/6级收缩期喷射性杂音，该处可触及震颤，胸骨左缘第3肋间有舒张期哈气样杂音，诊断是（）

A.冠心病合并心绞痛

B.肺动脉瓣关闭不全

C.肥厚型梗阻性心肌病

D.梅毒性心脏病

E.风湿性主动脉瓣狭窄合并关闭不全