A in astronomical telescope, the rays from the object after refraction at the objective are brought to a focus before entering the eyepiece to produce a real inverted image in front of the eye piece

B in Galileo's telescope, the rays from the object get refracted at the objective and are intercepted by the eyepiece before a real image is formed

C a line passing through the optical centre of the objective traversing through the eyepiece, is called line of sight

D the line of sight which passes through the intersection of cross-lines marked on a diaphragm fixed in front of the eyepiece in a plane at right-angles to the axis, is called the line of collimation

E all the above.