Final answer:
Under U.S. GAAP, companies may choose to recognize actuarial gains and losses in income immediately or amortize them over the expected service lives of employees.
Step-by-step explanation:
Under U.S. GAAP (Generally Accepted Accounting Principles), companies may choose to recognize actuarial gains and losses in income immediately or amortize them over the expected service lives of employees. This means that both options, recognizing the gains and losses immediately or amortizing them, are allowed under U.S. GAAP.