Light emerges out uniformly from a point source placed at the focus of a concave mirror to give out a spherical wave front. As a result of reflection of the paraxial rays from the concave mirror, according to Huygen's theory the reflected light is in the form of a

A

spherical wave front with centre at the focus, and radius equal to the radius of curvature of the mirror

B

spherical wave front with centre at the focus, and radius equal to the focal length of the mirror

C

cylindrical wave front with its axis coinciding with the principal axis of the mirror

D

plane wave front perpendicular to the reflected beam