Given A=(1201)A = \begin{pmatrix} 1 & 2 \\ 0 & 1 \end{pmatrix}A=(1021), which of the following is the inverse A−1A^{-1}A−1?
(1−201)\begin{pmatrix} 1 & -2 \\ 0 & 1 \end{pmatrix}(10−21)
(1201)\begin{pmatrix} 1 & 2 \\ 0 & 1 \end{pmatrix}(1021)
(−120−1)\begin{pmatrix} -1 & 2 \\ 0 & -1 \end{pmatrix}(−102−1)
(10−21)\begin{pmatrix} 1 & 0 \\ -2 & 1 \end{pmatrix}(1−201)