设 $A, B$ 为随机事件. 若 $0 < P(A) < 1,0 < P(B) < 1$, 则 $P(A \mid B)>P(A \mid \bar{B})$ 的充分必要条件 是
A. $P(B \mid A)>P(B \mid \bar{A})$.
B. $P(\underline{B} \mid A) < P(B \mid \bar{A})$.
C. $P(\bar{B} \mid A)>P(B \mid \bar{A})$.
D. $P(\bar{B} \mid A) < P(B \mid \bar{A})$.