Which of the following matrices is singular (non-invertible)?
(3241)\begin{pmatrix} 3 & 2 \\ 4 & 1 \end{pmatrix}(3421)
(25−13)\begin{pmatrix} 2 & 5 \\ -1 & 3 \end{pmatrix}(2−153)
(6231)\begin{pmatrix} 6 & 2 \\ 3 & 1 \end{pmatrix}(6321)
(1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)