Two stars of masses m₁ and m₂ are parts of a star system. The radii binary of their orbits are r₁ and r₂ respectively, measured from the centre of mass of the system. The magnitude of gravitational force m₂ exerts on ${\mathrm{m}}_1$, is

• A

  $\frac{{\mathrm{m}}_1{\mathrm{m}}_2\mathrm{G}}{{\left({\mathrm{r}}_1+{\mathrm{r}}_2\right)}^2}$

• B

  $\frac{{\mathrm{m}}_1\mathrm{G}}{{\left({\mathrm{r}}_1+{\mathrm{r}}_2\right)}^2}$

• C

  $\frac{{\mathrm{m}}_2\mathrm{G}}{{\left({\mathrm{r}}_1+{\mathrm{r}}_2\right)}^2}$

• D

  $\frac{\mathrm{G}\left({\mathrm{m}}_1+{\mathrm{m}}_2\right)}{{\left({\mathrm{r}}_1+{\mathrm{r}}_2\right)}^2}$