When Calculating the Present Value of an Ordinary Annuity,it Is

When calculating the present value of an ordinary annuity,it is assumed that:

A) cash flows will be reinvested at the required rate of return.
B) cash flows occur at the end of each accounting period.
C) the investor will wait until the end of the investment period to withdraw cash flows.
D) cash flows will be reinvested at the required rate of return and cash flows occur at the end of each accounting period.