Your father has $500,000 invested at 8%, and he now wants to retire. He wants to withdraw $50,000 at the beginning of each year, starting at the beginning of this year. How many years will it take to exhaust his funds, i.e., run the account down to zero? Select one: a. 20.91 years b. 17.54 years c. 20.27 years d. 26.72 years e. 18.49 years