Answer: Option B
$$\eqalign{
& {\text{Principal}}\,\,\,\,\,\,\,{\text{Amount}} \cr
& \underbrace {\,\,\,\,\,{\text{6000}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{7200}}\,\,\,\,\,}_{ + 1200} \cr
& {\text{By using formula,}} \cr
& {\text{Rate }}\% \cr
& = \frac{{1200}}{{6000}} \times \frac{{100}}{4} \cr
& {\text{ = 5}}\% \cr
& {\text{New rate}}\% \cr
& = {\text{5}} \times \frac{3}{2} = {\text{7}}{\text{.5}}\% \cr
& {\text{Interest after 5 years}} \cr
& = \frac{{6000 \times 7.5 \times 5}}{{100}} \cr
& {\text{ = Rs}}{\text{. 2250}} \cr
& {\text{Hence,}} \cr
& {\text{amount }} \cr
& {\text{ = Rs}}{\text{. }}\left( {6000 + 2250} \right) \cr
& {\text{ = Rs 8250}} \cr} $$