The table below displays the private marginal benefit, the private marginal cost, and the external marginal cost for Lisa's mining company. Quantity (units) Private MB Private MC External MC 100 $1,000 $700 $150 200 900 750 150 300 800 800 150 400 700 850 150 500 600 900 150 Lisa's mining company pollutes a local river during the production process. For each 100 units produced, the external cost of the pollution is $150. What is the socially optimal amount of mining for Lisa to produce