The Firms in a Market Have Decided Not to Compete

The firms in a market have decided not to compete with one another and have agreed to limit output and raise price.

A) This practice is known as concentrating and is legal in the United States and Canada.
B) This practice is known as collusion and is illegal in the United States.
C) In this way firms take advantage of economies of scale.
D) This is an effective barrier to entry, but is illegal in the United States.