The profitability index (PI) rule can be best stated as: a. An investment is acceptable if its Pl is less than one. b. An investment is acceptable if its Pl is greater than the internal rate of return (IRR). O c. An investment is acceptable if its Pl is less than its payback. O d. An investment is acceptable if its Pl is greater than one. e. An Investment is acceptable if its Pl is less than the net present value (NPV)