Suppose That Total Sales in an Industry in a Particular

Suppose that total sales in an industry in a particular year are $800 million and sales by the top four sellers are $50 million, $40 million, $30 million, and $30 million, respectively. We can conclude that

A) allocative efficiency will be achieved.
B) this industry is monopolistically competitive.
C) the concentration ratio is 25 percent.
D) firms in this industry likely collude with each other.