A Metropolitan district is considering three alternative designs (D1, D2, D3) for a major water infrastructure project with a projected economic life of 15 years and interest rate of 8.5% per annum.

For each option, the Table below shows the construction cost (CT), annual maintenance and operating cost (MC) and annual net benefits (B) to the host and nearby communities. Given that the options are mutually exclusive, use cost-benefit analysis to establish which option should be built.

Confirm your answer using NPV scores.

Options	CT ( million)	MC ( million)	B ( million)
D1	7.5	0.111	2.13
D2	8.4	0.125	2.45
D3	9.3	0.205	2.53