慢性风湿性心脏瓣膜病的主要致死原因为（）

A.脑出血

B.心律失常

C.心力衰竭

D.心源性休克

E.尿毒症

Which item of lifeboat equipment would be most suitable for night signaling to a ship on the horizon?（）

A.A red parachute flare

B.A red hand-held flare

C.A flashlight

D.A lantern