Omega Enterprises is reviewing two potential projects. Both require an initial investment of JPY 5,000,000. The expected cash inflows are as follows:

Year	Cash Flows (Project C)	Cash Flows (Project D)
Initial Investment	(5,000,000)	(5,000,000)
1	1,500,000	1,000,000
2	1,500,000	2,000,000
3	1,000,000	2,500,000
4	1,000,000	3,000,000

Requirements: a. Compute the payback period for both projects. b. Calculate the NPV for each project if the cost of capital is 6%. c. Which project should Omega Enterprises invest in based on the NPV criterion?