Which of the following is not a valid method of modifying cash flows to produce a mirr? a. turn multiple negative cash flows into a single negative cash flow by summing all negative cash flows over the project's lifetime. b. leave the initial cash flow alone and compound all of the remaining cash flows to the final period of the project. c. discount all of the negative cash flows to the present and compound all of the positive cash flows to the end of the project. d. discount all of the negative cash flows to time 0 and leave the positive cash flows alone.