Final answer:
A per se antitrust violation is characterized by the fact option c. that there is no need to prove intent for actions like price fixing; these actions are automatically illegal due to their inherently anticompetitive nature.
Step-by-step explanation:
The defining characteristic of a per se antitrust violation is that no intent needs to be proven for actions such as price fixing, bid rigging, or creating market allocations. These are considered so harmful to competition that the mere presence of the act is illegal, without the need for further investigation into the harmful effects or the intent behind the actions. Unlike other antitrust violations, which may require a detailed analysis of their effect on the market and intent, per se violations are a clear-cut breach of antitrust laws.