Which of the Following Choices Best Illustrates the Concept of Adam

Which of the following choices best illustrates the concept of Adam Smith's ―invisible hand‖?

A) A Vietnamese farmer grows rice; an exporter ships it to the United States, and a grocer in New York sells it to a customer.
B) A fishery's stock of fish becomes depleted due to overfishing as boats from around the world converge.
C) A government regulates a firm to clean up the pollutants it has released as part of its production process.
D) An apartment building is built, which provides much needed housing, on the site of the only playground for children in that town.