# If the rank of the matrix$\begin{bmatrix} \lambda & -1 & 0 \\0 & \lambda & -1 \\-1 & 0 & \lambda \end{bmatrix}$ is $2$, than $\lambda$ is
$\begin{array}{1 1} (1) 1& (2)2\\ (3) 3& (4) any\; real\; number\end{array}$