A paint firm has just announced that it will be building a new plant in a small town that is currently experiencing a high level of unemployment. The new plant will create 500 new jobs in the area and will occupy unused land at the edge of town. The plant will also dump some harmful chemicals into the town's river. From an economic standpoint this dumping of chemicals
a. creates a positive externality. b. is unimportant since the firm is reducing the unemployment in the region. c. is the production of a public good. d. creates a negative externality.