A source of light lies on the angle bisector of two plane mirrors inclined at an angle $\theta$. The values of $\theta$, so that the light reflected from one mirror does not reach the other mirror will be :
(a) $\theta>120^{\circ}$
(b) $\theta>90^{\circ}$
(c) $\theta \leqslant 120^{\circ}$
(d) none of these