Operations at the Green Hills Gold Mine are continuously releasing mercury into the headwaters of the Apache River, and most fish in the Apache River now have mercury levels at or above the legal limit for human consumption. With the price of gold rising, forcing more and more mining at Green Hills, there seems no hope for food fishing along the Apache River. Which of the following plans, if feasible, would allow the state to assist the food fishing industries along the Apache? ['The state bank will start to buy up large amounts of gold, preferentially buying directly from the Green Hills mines.', 'The state will mount a public awareness campaign, educating private citizen and restaurateurs about the dangers of high levels of mercury in food fish.', 'State workers will test the algae and underwater plants for mercury, removing those above a certain mercury threshold. These algae and plants are the principal food source of the food fish.', 'Immediately downstream from Green Hills, the state will install a sophisticated ionic filtration plant, which will substantially reduce the level of heavy metals (including mercury) in the water.']