Two solid spheres each of radius ' $R$ ' made of same material are placed in contact with each other. If the gravitational force acting between them is F, then

• Correct answer
  A

  $F \alpha R^4$
• B

  $F \alpha R^3$
• C

  $F \alpha R^2$
• D

  $F \alpha R$

Hence, the correct answer is option: 'A'.