Which one of the following statements is correct concerning capital budgeting? Selectone: a. If all machines function the same, we can use the NPV method to select the best machine even if we have only the cash outflows. b. The positive return on stock investment implies positive NPV. c. When analyzing several projects with different period, we have to estimate NPV over the greatest common divisor of all projects' periods. d. We have to use the same discount rate for the projects we analyze. e. For mutually exclusive projects, both Pl and IRR lead to the same conclusion