If $A$ and $B$ are two skew symmetric matrices of same order, then $AB$ is symmetric matrix if

In a third order matrix $A, a_{ij}$ denotes the element in the $i^{\mathrm{th}}$ row and $j^{\mathrm{th}}$ column.

If $a_{ij}=0$ for $i=j$
        $=1$ for $i>j$
        $=-1$ for $i<j$

Then the matrix is

Let $A=\left[a_{ij}\right]$ is a square matrix of order $2$ where $a_{ij}=i^2-j^2$. Then $A$ is