主动脉瓣狭窄，可出现

A．心尖部舒张期震颤

B．胸骨左缘第2肋间收缩期震颤

C．胸骨左缘第2肋间连续性震颤

D．胸骨右缘第2肋间收缩期震颤

E．胸骨右缘第2肋间舒张期震颤

The manager of a pension fund determines that during the past five years 85 percent of the stocks in the portfolio have paid a dividend and 40 percent of the stocks have announced a stock split. If 95 percent of the stocks have paid a dividend or announced a stock split, the joint probability of a stock paying a dividend and announcing a stock split is closest to:（）

A. 30%.

B. 45%.

C. 55%.