The set of all values of $\lambda$ for which the system of linear equations : $2x_1 -2x_2+x_3 =\lambda x_1 ; 2x_1 -3x_2+2x_3 =\lambda x_2 ; -x_1 +2x_2 =\lambda x_3$ has a non- trivial solution ,

Question

$\begin{array}{1 1} \text{is an empty set } \\ \text{is a singleton}\\ \text{contain two elements }\\ \text{contains more than two elements }\end{array}$