Why is interest cost a component of pension expense for a defined benefit pension plan?
a. it is the amount by which the pension fund must grow for the year to maintain funded status
b. PBO is an unpaid liability which increases as time passes; the sponsoring firm is responsible for PBO
c. plan assets are measured at fair value
d. it is the total increase in PBO for a period
e. it is the amount interest that must be included in the annual funding contribution.