Cast Inc. is finding that its employees are retiring closer to age 65 than to age 70. As a result, employees recently amended their defined benefit pension plan such that benefits will begin at age 63 instead of at age 68. Cast Inc. has been able to measure the actuarial present value of this amendment. How will this affect pension expense in current and future periods? O a. Prior service cost will increase and, as prior service cost is amortized, future pension expense will increase. O b. Prior service cost will decrease and, as prior service cost is amortized, future pension expense will decrease. O c. Pension expense will decrease immediately. O d. It will not have any impact on pension expense until the employees retire. O e. Pension expense will increase immediately