5-72. DorisWade purchased a condominium for $50,000 in 1987. Her down payment was $20,000. She financed the remaining amount as a $30,000, 30-year mortgage at 7%, compounded monthly. Her monthly payments are

$200. It is now 2007 (20 years later) and Doris has sold the condominium for $100,000, immediately after making her 240th payment on the unit. Her effective annual internal rate of return on this investment is closest to which answer below? (5.6)

(a) 3.6%

(b) 8.5%

(c) 5.3%

(d) 1.5%