A small block slides without friction down an inclined plane starting from rest. Let $S_n$ be the distance travelled from time $t- n-1$ to $t=n$. Then $\large\frac{S_n}{S_{n_1}}$ is

Question

$\begin{array}{1 1} \large\frac{2n-1}{2n} \\ \large\frac{2n+1}{2n-1} \\ \large\frac{2n-1}{2n+1} \\\large\frac{2n}{2n+1}\end{array}$