A Lens Forms an Erect Image of a Real Object

Multiple Choice

A lens forms an erect image of a real object.The image is twice the size of the object and appears to be 40 cm from the lens.Determine the power of the lens in diopters (D) .

A) There is not sufficient information.
B) -2.5 D
C) +2.5 D
D) +7.5 D
E) None of these is correct.