You intend to invest four annual payments, starting immediately: $10,000 now, another $10,000 at the end of year 1, $12,000 at the end of year 2, and $15,000 at the end of year 3. How much will you have at the end of year 4 if the fund is always earning 6% compounded annually?

a. $53,918.13

b. $54,417.52

c. $57,685.30

d. $57,894.77