(3)设(X1,X2,···,Nn)是来自正态总体N(0,σ^2)的一个简单随机样本,则下列-|||-统计量中服从F-分布的是 ()-|||-A. _(1)=dfrac ({{X)_(1)}^2+({X)_(2)}^2+({X)_(3)}^2}({{X)_(4)}^2+({X)_(5)}^2+... +({X)_(9)}^2} B. _(2)=dfrac ({{X)_(1)}^2+({X)_(2)}^2+({X)_(3)}^2+({X)_(4)}^2}({{X)_(4)}^2+({X)_(5)}^2+({X)_-|||-C. _(3)=dfrac ({{X)_(1)}^2+({X)_(2)}^2+({X)_(3)}^2}(2({{X)_(4)}^2+({X)_(3)}^2+... +({X)_(3)}^2 D. _(4)^2=dfrac (2({{X)_(1)}^2+({X)_(2)}^2+({X)_(3)}^2)}({{X)_(4)}^2+({X)_(5)}^2+... +({X)_(9)