. (i) State an example of a cartel that has been reasonably successful at controlling prices in the post-WWII period.

(ii) Provide a simple legal reason why cartels are difficult to maintain in practice in the United States.

(iii) Use the results from the cartelization model described in class to briefly explain why some professional associations (e.g., Colorado Society of Certified Public Accountants) may use certification standards to prevent new candidates from practicing in their profession.