A project your firm is considering for implementation has these estimated costs and revenues: an investment cost of Php500,000; maintenance costs that start at Php50,000 at EOY one and increases by Php10,000 for each of the next four years, and then remain constant for the following five years; savings of Php200,000 per year; and a resale value of Php350,000 at the end of study period. If the project has a 10-year life and the firm's MARR is 10% per year, justify the economics of the project based on the following methods:

A. Annual Worth method

B. Conventional Payback method

C. External Rate of Return method D. Modified Benefit-Cost Ratio method