Suppose the gravitational force varies inversely as the $n^{th}$ power of distance. Then the time period planet in circular orbit of radius $R$ around the sun will be proportional to

Question

( A ) $R^{(\frac{n+1}{2})}$
( B ) $R^{(\frac{n-1}{2})}$
( C ) $R^{(\frac{n-2}{2})}$
( D ) $R^n$