Which of the following matrices is skew-symmetric (i.e., AT=−AA^T = -AAT=−A)?
(1223)\begin{pmatrix} 1 & 2 \\ 2 & 3 \end{pmatrix}(1223)
(03−30)\begin{pmatrix} 0 & 3 \\ -3 & 0 \end{pmatrix}(0−330)
(2112)\begin{pmatrix} 2 & 1 \\ 1 & 2 \end{pmatrix}(2112)
(1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)