We know that according to the law of gravitation, the gravitational force between any two bodies that have some mass is given as:

${\text{F}}_{ }=\text{G}.\frac{{\text{m}}_{\text{1}}{\text{m}}_{\text{2}}}{{\text{r}}_{ }^2}$
Where m₁ and m₂ are the masses of the two bodies, r is the distance between them and G is the universal gravitation constant.
$G= 6.67 X {10}^{-11} N{m}^2/k{g}^2$

The value of G is constant for any two bodies involved and is independent of the medium in which the bodies lie.

Here, we can see that we have written the value of G in the SI unit system. If we change the units to the MKS system, then due to conversion factors the value of G will also change.

Therefore, option A is the correct answer.