Which of the following vectors is an eigenvector of A=(3113)A = \begin{pmatrix} 3 & 1 \\ 1 & 3 \end{pmatrix}A=(3113)?
(11)\begin{pmatrix} 1 \\ 1 \end{pmatrix}(11)
(10)\begin{pmatrix} 1 \\ 0 \end{pmatrix}(10)
(01)\begin{pmatrix} 0 \\ 1 \end{pmatrix}(01)
(12)\begin{pmatrix} 1 \\ 2 \end{pmatrix}(12)