When Calculating the Present Value of an Ordinary Annuity, It

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B) cash flows are withdrawn at the end of each year.
C) the investor will wait until the end of the investment period to withdraw cash flows.
D) Both cash flows will be reinvested at the required rate of return and cash flows are withdrawn at the end of each year are correct.