Answer:
c. the level at which the marginal social cost is equal to the marginal social benefit.
Step-by-step explanation:
Optimal level of Pollution is defined as the level of pollution whereby social welfare is maximized by equating the marginal cost of additional pollution with the marginal benefit.
The concept of the optimal level as expressed by Socio-Economist, recognizes that there is benefits to allowing pollution, such that, it is not efficient to reduce pollution to zero. Because, the cost of this reduction would probably exceed the benefits.
In other words, the benefits that will be derived from the optimum pollution would be lost if pollution is to be eliminated.