In my economics class, we are learning about optimum amount. We were given this practice question to do, but I can't figure it out. Could someone explain it to me, and how to go about it?

Q: The damage and abatement (pollution reduction) cost for each amount of pollution is in a table below. What is the optimum amount of pollution? Emissions - tonnes/year Total Damage Costs ($) Total Abatement Costs 10,000,000 88,000,000 3,000,000 9,000,000 66,000,000 4,350,000 8,000,000 48,000,000 10,050,000 7,000,000 33,600,000 17,100,000 6,000,000 22,400,000 25,500,000 5,000,000 14,000,000 35,250,000 4,000,000 8,000,000 46,350,000 3,000,000 4,000,000 58,800,000 2,000,000 1,600,000 72,600,000 1,000,000 400,000 87,750,000 0 0 104,250,000 Select one: O a. 2,000,000 metric tonnes/year O b. 7,000,000 metric tonnes/year O c. 9,000,000 metric tonnes/yearSelect one: O a. 2,000,000 metric tonnes/year O b. 7,000,000 metric tonnes/year O c. 9,000,000 metric tonnes/year O d. 6,000,000 metric tonnes/year O e. 3,000,000 metric tonnes/year Of. 5,000,000 metric tonnes/year O g. 8,000,000 metric tonnes/year O h. 1,000,000 metric tonnes/year O i. 0 pollution O j. 10,000,000 metric tonnes/year O k. 4,000,000 metric tonnes/year