Ankur invested a sum of $\text{Rs. }16,800$ for four years in a financial scheme. The rate of interest in the scheme is $8\%$ per annum compounded yearly for the first two years and $10\%$ per annum for the 3rd and 4th years compounded yearly. What will be the cumulative compound interest at the end of 4 years?

1. A
   $\text{Rs. }6810$
2. B
   $\text{Rs. }6910$
3. C
   $\text{Rs. }6540$
4. D
   $\text{Rs. }6210$