Answer:
(b) 12.55%
Explanation:
The effective interest rate, also known as the annual equivalent rate (AER) or annual percentage rate (APR), represents the true annual cost of borrowing or the actual yield on an investment, taking into account compounding interest over a specified period.
The formula to calculate the effective interest rate for a given nominal interest rate compounded n times per year is:

where:
- r is the nominal interest rate (as a decimal),
- n is the number of compounding periods per year.
In this case:
- r = 12% = 0.12
- n = 4 (compounded quarterly)
Substitute these values into the formula and solve for AER:





Converting this to a percentage and rounding to the nearest hundredth gives:

Therefore, the effective interest rate is 12.55%.