How Are the Accrued Benefits of a Defined Benefit Plan

How are the accrued benefits of a defined benefit plan measured?

A) They are measured as the difference between the carrying value of the plan's assets and the liability to pay funds out to members on retirement.
B) They are measured as the market value of the assets of the plan with no accumulated depreciation deducted.
C) They are a residual amount: the difference between the carrying amount of the assets and the sum of the income tax and sundry liabilities of the plan.
D) They are measured in a detailed actuarial review to determine the present value of expected future benefit payments arising as a result of membership of the fund up to measurement date.