The Cost of Controlling Emissions at a Firm Goes Up

Multiple Choice

The cost of controlling emissions at a firm goes up rapidly as the amount of emissions reduced goes up. Here is a possible model: where q is the reduction in emissions (in pounds of pollutant per day) and C is the daily cost (in dollars) of this reduction. If a firm is currently reducing its emissions by 7 pounds each day, what is the marginal cost of reducing emissions even further?

A) $1,400
B) $2,800
C) $7,800
D) $2,100
E) $700