An annuity is a series of equal payments occuring at equal time intervals, and this amount includes the sum of all payments plus interest, if allowed to accumulate at a definite rate of interest from the time of initial payment to the end of annuity term. Ordinary annuity is used in the calculation of the

• A. manufacturing cost.
• B. depreciation by sinking fund method.
• C. discrete compound interest.
• D. cash ratio.