The correct option is B Image A is real, whereas image B is virtual.
A real image is formed when rays of light, upon reflection from the object, actually converge at a point. Thus, they can be caught on a screen.
Here, image A is formed on a screen. Hence it is a real image.
In front of the screen, a plane mirror is placed. The image B, which is an image of the image A, is virtual. This is because the rays of light, upon reflection from the plane mirror, appear to diverge from B.