$\text { If } A=\left(\begin{array}{ll}1 & 0 \\0 & 1\end{array}\right) \text { then, } A^{4}=\text { ? }$

$\left(\begin{array}{ll}1 & 0 \\0 & 1\end{array}\right)$

$\left(\begin{array}{ll}1 & 0 \\1 & 1\end{array}\right)$

impossible

$\left(\begin{array}{ll}1 & 1 \\0 & 1\end{array}\right)$