A light ray is incident on a horizontal plane mirror at an angle of $45^{\circ}$. At what angle should a second plane mirror be placed in order that the reflected ray finally be reflected horizontally from the second mirror, as shown in figure:
(a) $\theta=30^{\circ}$
(b) $\theta=24^{\circ}$
(c) $\theta=22.5^{\circ}$
(d) $\theta=67.5^{\circ}$