Which of these matrices is skew-symmetric (AT=−AA^T = -AAT=−A)?
(02−20)\begin{pmatrix} 0 & 2 \\ -2 & 0 \end{pmatrix}(0−220)
(1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)
(0220)\begin{pmatrix} 0 & 2 \\ 2 & 0 \end{pmatrix}(0220)
(1221)\begin{pmatrix} 1 & 2 \\ 2 & 1 \end{pmatrix}(1221)