A project has a discounted payback period that is equal to the required payback period. Given this, which of the following statements must be true? I. The project must also be acceptable under the payback rule. II. The project must have a profitability index that is equal to or greater than 0 . III. The project must have a zero net present value. IV. The project's internal rate of return must equal the required return. I, III, and IV only I only II and III only I and II only I and III only