A certain sum amounts to ₹8,640 in 2 years at simple interest and to ₹9,720 in 3 years. The sum (in ₹) and the rate of inerest p.a., respectively, are:

A

₹6,450 and $$15\%$$

B

₹6,450 and $$16\frac{2}{3}\%$$

C

₹6,480 and $$16\frac{2}{3}\%$$

D

₹6,480 and $$15\%$$