If you have a lens with optical power -4.0 D and you place an object 25 cm in front of it, which of the following statements about the image of the object is correct?
a) The image is virtual and located 25 cm in front of the lens.
b) The image is real and located 25 cm in front of the lens.
c) The image is virtual and located 50 cm behind the lens.
d) The image is real and located 50 cm behind the lens.