Two spheres of masses m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific density 3. The gravitational force will now be :

• A

  3F

• B

  F

• C

  $\frac{\mathrm{F}}{3}$

• D

  $\frac{\mathrm{F}}{9}$