Imagine a light planet revolving around a very massive star in a circular orbit of radius R with a period of revolution T. If the gravitational force of attraction between planet and star is proportional to \[{{R}^{-\frac{5}{2}}}\], then \[{{T}^{2}}\] is proportional to [IIT 1989; RPMT 1997]

• A. \[{{R}^{3}}\]
• B.  \[{{R}^{7/2}}\]
• C.  \[\frac{n{{r}^{2}}}{{{({{x}^{2}}+{{r}^{2}})}^{3/2}}}\]
• D. \[{{R}^{3/2}}\]