GreenTech Ltd. has to choose between two mutually exclusive projects. The projected cash flows are as follows:

Project	Initial Investment ($)	Year 1 ($)	Year 2 ($)	Year 3 ($)	Year 4 ($)	IRR (%)
C	70,000	20,000	25,000	30,000	35,000	18.00
D	80,000	25,000	30,000	35,000	40,000	20.50

The cost of capital is 15%.

Requirements: a) Explain why relying solely on IRR might lead to a wrong decision. b) Calculate the NPV for both projects. c) Recommend which project should be accepted. d) Discuss the impact of different capital costs on the decision.