Which of the following is NOT a probability distribution（）

A. Flip a coin: P(H)=P(T)=0.5.

B. Roll an irregular die: P(1)=P(2)=P(3)=P(4)=0.2 and P(5)=P(6)=0.1.

C. Zeta Corp. : P(dividend increases)=0.60, P(dividend decreases)=0.30.

休克的根本病因是（）

A.血压下降

B.中心静脉压下降

C.心排出量下降

D.有效循环血量下降

E.微循环障碍