Churchill Inc. is a public company operating under U.S. GAAP that offers its former employees postretirement benefits. Which of the following statements is most accurate regarding Churchill's nonpension benefits?

a. The cost associated with retiree benefits may be accrued before services are rendered, as long as they can be reasonably estimated.

b. Any differences between the expected and actual returns must be recognized in the income statement in the period incurred.

c. The EPBO for the benefits will be equal to or greater than the APBO as a result of any nonvested benefits.

d. Although the assumed health care trend rate is critical to the company's estimates, it is not a required disclosure.