Leo is 40 years old and has finally realized he needs to be investing for his retirement. He has decided he will work and invest annually (at the end of every year) until he has accumulated $900,000 in his account. The account is earning an average of 8.5% per year. If Leo can invest $6,500 every year, how many years until he can retire? Select one: a. 23.4 years b. 31.2 years c. 32.8 years d. 25.0 years