Consider the diagram in Problem 31-4, and answer the following questions.

a. Suppose that a new technology for reducing water pollution generates a reduction in the marginal cost of pollution abatement at every degree of water cleanliness. After this event occurs, will the optimal percentage degree of water cleanliness rise or fall? Will the cost incurred for the last unit of water cleanup increase or decrease? Provide a diagram to assist in your explanation.
b. Suppose that the event discussed in part (a) occurs and that, in addition, medical studies determine that the marginal benefit from water pollution abatement is higher at every degree of water cleanliness. Following both events, will the optimal percentage degree of water cleanliness increase or decrease? In comparison with the initial optimum, can you determine whether the cost incurred for the last unit of water cleanup will increase or decrease? Use a new diagram to assist in explaining your answers.

Marginal benefit 16 10 Marginal cost 65 85 98 100 0 Degree of Cleanliness (96)