下列矩阵中是正定矩阵的为（ ）
A
$\left(\begin{array}{ll}2 & 3 \\ 3 & 4\end{array}\right)$
B
$\left(\begin{array}{ll}3 & 4 \\ 2 & 6\end{array}\right)$
C
$\left(\begin{array}{ccc}1 & 0 & 0 \\ 0 & 2 & -3 \\ 0 & -3 & 5\end{array}\right)$
D
$\left(\begin{array}{lll}1 & 1 & 1 \\ 1 & 2 & 0 \\ 1 & 0 & 2\end{array}\right)$
E
F