A chemical discharge from the Adidas factories along the Pearl River in China causes a total damage worth of $50 million in 25 years. Imagine, the Chinese government decides to demand that damage cost this year (2020) from the International sports garment companies through a tax policy. However, Environmental Ministry uses a discount factor of 1 and comes up with a Net Present Value while the Commerce Ministry uses a 10% discount rate and comes up with another Net Present Value of the damage cost. a) Calculate both the NPVs and explain which discount rate offers a more sustainable option in this case.