A) A project which costs $80k today and earns $20k every year in perpetuity has a payback period of 4 years. B) The internal rate of return, IRR, is computed from a projects cash flows by setting the NPV formula equal to zero. C) The IRR approach is useful when a proper risk-adjusted discount rate for a project is not easy to estimate. D) The payback period rule is the method most popular with CFOs.