In the US,Firms That Engage in Cooperative Efforts to Coordinate Pricing

In the U.S.,firms that engage in cooperative efforts to coordinate pricing

A) are always in violation of antitrust laws.
B) may face federal charges of illegal collusion if they cannot provide evidence that the coordination of prices was in the best interest of consumers.

C) are simply trying to reach a Nash equilibrium and are not viewed by courts as necessarily breaking any laws.
D) both b and C