A suitable unit for gravitational constant is [MNR 1988]

• A. \[kg\text{-}\,m{{\sec }^{-1}}\]
• B. \[N\ {{m}^{-1}}\sec \]
• C. \[N\,\,{{m}^{2}}\,k{{g}^{-2}}\]
• D. \[kg\,m\,{{\sec }^{-1}}\]