A corporate bond allows its holders to recover 8.68 percent of the price they pay for the bond in the first year, 8.04 percent in the second year, 7.45 percent in the third year and the remainder in the fourth year (all in PV terms). What is the bond's duration in years?

2.75 years

3.24 years

3.98 years

3.50 years

4.14 years