Suppose there is an oligopoly in the bottled cold coffee industry. Which of the following is probably the most significant barrier to entry?

a. The existing firms have expertise in using game theory strategies.
b. No patents have been granted to the existing firms in the industry.
c. The existing firms own most of the coffee bean plantations.
d. There are no tariffs imposed on coffee bean imports.

c. The existing firms own most of the coffee bean plantations