Nelson borrowed $5000 for 4. 5 years. For the first 2. 5 years, the interest rate on the loan was 8. 4% compounded monthly. Then the rate became 7. 5% compounded semiannually. What total amount was required to pay off the loan if no payments were made before the expiry of the 4. 5-year term?
a) $6438. 82
b) $6537. 24
c) $6635. 76
d) $6734. 18