20. A situation in which taking one investment prevents the taking of another is called: A) Net present value profiling. B) Operational ambiguity. C) IRR criterion D) Mutually exclusive investment decisions. E) None of the above. 21. The decision rule is considered the "best" in principle. A) internal rate of return B) payback period C) average accounting return D) Net IRR E) NPV 22. Project selection ambiguity can arise if one relies on IRR instead of NPV when: A) The first cash flow is negative and the remaining cash flows are positive. B) Projects are independent of one another. C) A project has more than one NPV. D) The profitability index is greater than one. E) Project cash flows are not conventional