Which of the following matrices is NOT diagonalizable over R\mathbb{R}R?
(1221)\begin{pmatrix} 1 & 2 \\ 2 & 1 \end{pmatrix}(1221)
(01−10)\begin{pmatrix} 0 & 1 \\ -1 & 0 \end{pmatrix}(0−110)
(1002)\begin{pmatrix} 1 & 0 \\ 0 & 2 \end{pmatrix}(1002)
(1102)\begin{pmatrix} 1 & 1 \\ 0 & 2 \end{pmatrix}(1012)