Which of the following matrices is symmetric?
(1231)\begin{pmatrix} 1 & 2 \\ 3 & 1 \end{pmatrix}(1321)
(1221)\begin{pmatrix} 1 & 2 \\ 2 & 1 \end{pmatrix}(1221)
(01−10)\begin{pmatrix} 0 & 1 \\ -1 & 0 \end{pmatrix}(0−110)
(1021)\begin{pmatrix} 1 & 0 \\ 2 & 1 \end{pmatrix}(1201)