The set of equations : $\lambda x-y+(\cos \theta) z=0 ; 3 x+y+2 z$
$=0 ;(\cos \theta) x+y+2 z=0,0 \leq \theta<2 \pi$, has non-trivial
solutions.
(A) for no values of $\lambda$ and $\theta$
(B) for all values of $\lambda$ and $\theta$
(C) for all values of $\lambda$ and only two values of $\theta$
(D) for only one value of $\lambda$ and all values of $\theta$