Which vector is an eigenvector of A=(1111)A = \begin{pmatrix} 1 & 1 \\ 1 & 1 \end{pmatrix}A=(1111)?
(1,1)(1, 1)(1,1)
(1,−1)(1, -1)(1,−1)
(1,0)(1, 0)(1,0)
(0,1)(0, 1)(0,1)