The convex surface of a concavo-convex lens of refractive index $$1.5$$ and radii of curvature $$R_1=20\,\text{cm}$$ and $$R_2=40\,\text{cm}$$ has been silvered so as to make it reflecting. The distance of a luminous object from the reflecting system when placed in front of it on its principal axis, so that the image coincides with the object is

A

$$40\,\text{cm}$$

B

$$32\,\text{cm}$$

C

$$16\,\text{cm}$$

D

$$8\,\text{cm}$$