$A=\left[\begin{array}{cc}1 & i \\-i & 1\end{array}\right],$$B=\left[\begin{array}{cc}i & -1 \\-1 & -i\end{array}\right]$ এবং $i=\sqrt{-1}$ হলে $AB$ এর মান কত?

$\left[\begin{array}{ll}1 & 0 \\0 & 1\end{array}\right]$

$\left[\begin{array}{ll}0 & 0 \\0 & 0\end{array}\right]$

$\left[\begin{array}{ll}\mathrm{i} & 0 \\0 & \mathrm{i}\end{array}\right]$

$\left[\begin{array}{ll}\mathrm{i} & 1 \\1 & \mathrm{i}\end{array}\right]$