Answer: Option C
Explanation: The given case is an example of violation of anti trust laws. Anti trust laws is collection of laws made by Govt. of America to protect the consumer benefit in the market.
A per se violation refers to the violation of anti trust law through any agreement or contract as such.
In the given case, the association has made an agreement within, that will result in consumer loss as it will hinder the competition in the market.
Thus, we can conclude that the boycott of group is violation of an anti trust law.