In justifying the law of reflection for a plane mirror using wavefronts, which reasoning correctly explains why the angle of incidence equals the angle of reflection?
(a) Because the component of light’s velocity parallel to the mirror is unchanged while the perpendicular component reverses, the angles measured to the normal must be equal
(b) Equal angles make the optical path between the incident and reflected wavefronts minimum, hence the mirror naturally chooses this path
(c) Secondary wavelets from every point on the incident wavefront take equal time to reach the new reflected wavefront only when the two angles are equal
(d) Energy conservation requires that the incident and reflected rays are symmetric about the normal, leading to equal angles