Which of the following statements is FALSE? A: The incremental IRR need not exist. B: If a change in the timing of the cash flows does not affect the NPV, then the change in timing will not impact the IRR. C: Although the incremental IRR rule can provide a reliable method for choosing among projects, it can be difficult to apply correctly. D: When projects are mutually exclusive, it is not enough to determine which projects have positive NPVs.