What is the result of I2×(abcd)I_2 \times \begin{pmatrix} a & b \\ c & d \end{pmatrix}I2×(acbd)?
(0000)\begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix}(0000)
(abcd)\begin{pmatrix} a & b \\ c & d \end{pmatrix}(acbd)
(dcba)\begin{pmatrix} d & c \\ b & a \end{pmatrix}(dbca)
(1111)\begin{pmatrix} 1 & 1 \\ 1 & 1 \end{pmatrix}(1111)