An object is placed in a medium of refractive index 3. An electromagnetic wave of intensity $$6 \times 10^8$$ W m$$^{-2}$$ falls normally on the object and it is absorbed completely. The radiation pressure on the object would be (speed of light in free space = $$3 \times 10^8$$ m s$$^{-1}$$) :

A

36 N m$$^{-2}$$

B

18 N m$$^{-2}$$

C

6 N m$$^{-2}$$

D

2 N m$$^{-2}$$