Antitrust laws in other countries are weak in comparison to U.S. antitrust laws

Refer to Figure 4-4. What is the value of consumer surplus at a price of $18?

A) $60 B) $120 C) $180 D) $240

Which of the following can be thought of as a barrier to entry?

A) scale economies. B) patents. C) strategic actions by incumbent firms. D) all of the above