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 the firm has released as part of its production process.
D) An apartment building that provides much-needed housing is built on the site of the only playground for children in that town.