Which of the following statements are incorrect for spherical mirrors.
(a) a concave mirror forms only virtual images for any position of real object
(b) a convex mirror forms only virtual images for any position of a real object
(c) a concave mirror forms only a virtual diminished image of an object placed between its pole and the focus
(d) a convex mirror forms a virtual enlarged image of an object if it lies between its pole and the focus.