What mechanism does U.S. GAAP employ such that the effects of a bull market in risky assets doesn't distort the P&L for a non-financial company that holds mostly risky assets in their defined benefit plan?

a. U.S. GAAP allows the difference between the actual return and the expected return of plan assets to completely bypass the P&L statement.

b. U.S. GAAP allows companies to spread out the gains or losses over time using the corridor approach instead of taking them in 1 accounting period.

c. U.S. GAAP allows companies to exclude pension related amortization if the funded status is in surplus.