What Is the Legal Significance of the Distinction Between "Rule

What is the legal significance of the distinction between "rule of reason" violations and per se violations under the Sherman Act?

A) Rule of reason violations must be proven beyond a reasonable doubt, while per se violations must be proven by a preponderance of the evidence.
B) Rule of reason violations require an agreement with at least one other party, but per se violations can occur without an agreement with others.
C) Rule of reason violations relate to horizontal restraints of trade, while per se violations relate to vertical restraints of trade.
D) Rule of reason violations relate to actions brought by private parties, and per se violations relate to actions brought by the government.
E) Rule of reason violations might be proven to be acceptable, but per se violations are not acceptable under any circumstances.