A certain sum amounts to ₹10,164 in 4 years and to ₹12,320 in $$7\frac{1}{2}$$ years at the same rate of interest per annum at simple interest. The sum and the rate of interest are, respectively:

A

₹7,800 and 8.5%

B

₹8,000 and 7%

C

₹7,700 and 8%

D

₹7,500 and 9%