设函数 $f(x), g(x)$ 均有二阶连续导数, 满足 $f(0)>0, g(0) < 0$, 且 $f^{\prime}(0)=$ $g^{\prime}(0)=0$, 则函数 $z=f(x) g(y)$ 在点 $(0,0)$ 处取得极小值的一个充分条件是
A
$f^{\prime \prime}(0) < 0, g^{\prime \prime}(0)>0$.
B
$f^{\prime \prime}(0) < 0, g^{\prime \prime}(0) < 0$.
C
$f^{\prime \prime}(0)>0, g^{\prime \prime}(0)>0$.
D
$f^{\prime \prime}(0)>0, g^{\prime \prime}(0) < 0$.
E
F