Which of the Following Statements Is True About Concentrated Industries

Which of the following statements is true about concentrated industries?

A) These industries have few competitors and rivalry is less intense.
B) Smaller competitors usually respond aggressively to actions taken by large firms.
C) Few large competitors are aware of each other's presence and therefore more likely to create conflict.
D) If firms are approximately the same size, they tend to be able to respond, or retaliate, strongly to moves by rival firms.