The magnitude of the gravitational field at distances $r_1$ and $r_2$ from the center of a uniform sphere of radius $R$ and mass $M$ are $F_1$ and $F_2$ respectively. The ratio $(F_1 / F_2)$ will be (if $r_1 > R$ and $r_2 < R$):

• A
  $\frac{R^2}{r_1 r_2}$
• B
  $\frac{R^3}{r_1 r_2^2}$
• C
  $\frac{R^3}{r_1^2 r_2}$
• D
  $\frac{R^4}{r_1^2 r_2^2}$