Who was the economist who first proposed that governments use taxes and subsidies to correct for externalities?

Facts, measurements, or statistics that describe the world are referred to as:

A) data. B) models. C) hypothesis. D) empiricism.

Which conditions must be present for "perfect competition" to occur?

A) A large number of buyers and sellers, and all of them enjoy full and complete information. B) Sellers produce identical products. C) There is a costless mobility of resources. D) Everybody behaves as a price taker. E) All of the above.