A thin convex lens L with a refractive index of 1.5 is placed on a plane mirror M. When a pin is placed at A such that AO is 18 cm, its real image is inverted.
A) The focal length of lens L is -6 cm.
B) The image is virtual and erect if the pin is moved closer to the lens.
C) The image is real and inverted.
D) The lens is a concave lens.