Which of the following matrices is equal to the product ATBA^T BATB where A=(1021)A = \begin{pmatrix} 1 & 0 \\ 2 & 1 \end{pmatrix}A=(1201) and B=(0110)B = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}B=(0110)?
(2110)\begin{pmatrix} 2 & 1 \\ 1 & 0 \end{pmatrix}(2110)
(0112)\begin{pmatrix} 0 & 1 \\ 1 & 2 \end{pmatrix}(0112)
(1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)
(2101)\begin{pmatrix} 2 & 1 \\ 0 & 1 \end{pmatrix}(2011)