If a document is to be produced using a duplicating camera, where should the camera be placed in or
der to obtain an exact copy? A. at the point which
is twice the focal lenght of the lens of the camera
B. at the optical centre of the lens of the camera C
between the principal and a point twice the foca
lens of the lens of the camera D. beyond a poin
twice the focal lenght of the lens of the camera​