Pick up the correct specification of Ramsden eyepiece from the following:
(A) It consists of two equal piano convex lenses
(B) The curved surfaces of Plano-convex lenses face each other
(C) The distance between the diaphragm and the front lens of the eyepiece is kept equal to 1/4
th of the focal length of a lens so that rays from a point on the diaphragm enter the eye as a
parallel beam
(D) All the above