Answer: Option B
Let the sum be Rs. P and rate of interest be R% per annum. Then,
$$\eqalign{
& P{\left( {1 + \frac{R}{{100}}} \right)^2} = 9680\,.....\,\left( 1 \right) \cr
& P{\left( {1 + \frac{R}{{100}}} \right)^3} = 10648\,.....\,\left( 2 \right) \cr} $$
On dividing equation (2) by (1) :
$$\eqalign{
& 1 + \frac{R}{{100}} = \frac{{10648}}{{9680}} \cr
& \Rightarrow \frac{R}{{100}} = \frac{{10648}}{{9680}} - 1 \cr
& \Rightarrow \frac{R}{{100}} = \frac{{10648 - 9680}}{{9680}} \cr
& \Rightarrow \frac{R}{{100}} = \frac{{968}}{{9680}} \cr
& \Rightarrow \frac{R}{{100}} = \frac{1}{{10}} \cr
& \Rightarrow R = \frac{1}{{10}} \times 100 \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\, = 10\% \cr} $$