In order to accumulate $15,500 at the end of four years, Pamela makes equal deposits at the beginning of each quarter into an account, which pays 4.2% interest compounded quarterly. The size of her quarterly payments is: a. $15,500 0.0105 1-1.0105-16 b. $15,500 0.0105 1.010516-1 $15,500 0.0105 1.0105 1.010516 - 1 d. C. $15,500 0.0105 1.0105 1-1.0105-16