help please

Which of the following statements about the Net Present Value (NPV) and Internal Rate of Return (IRR) methods of investment appraisal for a conventional project (an outflow followed by a series of inflows) is correct? O The IRR can be obtained exactly using interpolation whereas the graphical method provides only an approximate rate for the IRR. O If the NPV of an investment at r% is positive, the NPV will be lower at a rate of s% if s% is less than %. O The graph of the NPV against the discount rate has a positive slope. O An estimate of the IRR requires the calculation of the NPV at two different discount rates