Two investment opportunities, C and D, are presented with the following details:

Year	Project C Cash Flow ($)	Project D Cash Flow ($)
0	-200,000	-150,000
1	60,000	50,000
2	80,000	60,000
3	100,000	70,000
4	120,000	90,000
IRR	20%	22%

Cost of capital is 14%.

a) Calculate the payback period for each project. b) Compute the NPV of each project. c) Analyze which project should be preferred based on NPV. d) Discuss how the timing of cash flows affects the project's attractiveness.