A sphere of mass 40 kg is attrached by another of mass 15 kg when their centres are 0.2 mapart, with a force of\[\text{9}.\text{8}\times \text{l}{{0}^{-\text{7}}}\text{ N}\text{.}\] Calculate the constant of gravitation.

• A.  \[9.2\times {{10}^{-7}}N{{m}^{2}}k{{g}^{-2}}\]
• B.  \[6.13\times {{10}^{-11}}N{{m}^{2}}k{{g}^{-2}}\]
• C.  \[6.53\times {{10}^{-18}}N{{m}^{2}}k{{g}^{-2}}\]
• D.  \[6.53\times {{10}^{-11}}N{{m}^{2}}k{{g}^{-2}}\]