Mark Johnson saves a fixed percentage of his salary at the end of each year. This year he saved $3,500. For each of the next 5 years, he expects his salary to increase at an 4% annual rate, and he plans to increase his savings at the same 4% rate. There will be a total of 6 investments, the initial $3,500 plus five more. If the investments earn a return of 13% per year, how much will Mark have at the end of six years?

a. $34,778.28

b. $31,757.94

c.$23,215.41

d. $15,253.93