已知三个正态分布密度函数f _i (x) =
（x∈R，i = 1，2，3）的图象如图所示，则

A．m1＜m2 = m3，s1 = s2＞s3	B．m1＞m2 = m3，s1 = s2＜s3
C．m1 = m2＜m3，s1＜s2 = s3	D．m1＜m2 = m3，s1 = s2＜s3w_w