According to the Law of Reflection, If a Beam of Light

According to the law of reflection, if a beam of light strikes a flat mirror at an angle of 30 $\degree$ relative to a plane perpendicular to the surface of the mirror, at what angle will it reflect, relative to a plane perpendicular to the surface of the mirror?

A) 0 $\degree$
B) 30 $\degree$
C) 60 $\degree$
D) 90 $\degree$
E) 120 $\degree$