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%.

患者女性，42岁，以“发热伴胸闷不适1周”来诊。胸CT检查示左侧胸腔中等量积液。后行胸腔穿刺化验胸腔积液呈渗出液改变。关于胸腔积液的描述，下列哪项是错误的

A．外观浑浊、草绿色半透明

B．比重＞1.018

C．黏稠、不易抽出

D．可自凝

E．细胞数＜100×10⁶/L，以间皮细胞为主