已知函数 f(x)f\left( x\right)f(x) 的定义域为 R,f(xy)=y2f(x)+x2f(y)\mathbf{R},f\left( {xy}\right) = {y}^{2}f\left( x\right) + {x}^{2}f\left( y\right)R,f(xy)=y2f(x)+x2f(y) ,则 ( ).A. f(0)=0f\left( 0\right) = 0f(0)=0 B. f(1)=0f\left( 1\right) = 0f(1)=0C. f(x)f\left( x\right)f(x) 是偶函数 D. x=0x = 0x=0 为 f(x)f\left( x\right)f(x) 的极小值点