设随机变量X的概率密度为(x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)}((x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)}),则(x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)}A. (x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)} B. (x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)} C. (x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)} D. (x)=dfrac (1)(2sqrt {pi )}(e)^-dfrac ({(x-3)^2)(4)}

设随机变量X的概率密度为(),

则

A.
B.
C.
D.