Hi Hari,

please se the answer below. Hope it helps you

S=ut+0.5at^{2}= 0.5at^{2} (since u=0)

At t=n-1

S= 0.5a(n-1)^{2}

At t=n

S'=0.5a(n)^{2}

S_{n}= S'-S =0.5 [n^{2} - (n-1)^{2}] = 0.5a (n-n+1)*(n+n-1)

S_{n}= 0.5a*(2n-1)

put n+1 in place of n in expression of S_{n}

S_{n+1}= 0.5a (2(n+1)-1)= 0.5a (2n+1)

**S**_{n}/S_{n+1} = 2n-1/2n+1

**So the correct option is (C)**