The De Beers Company Blocked Competition

The De Beers Company blocked competition

A) in the diamond market by controlling the output of most of the world's diamond mines.
B) by controlling the supply of most of the world's high-quality bauxite, the mineral used to produce aluminum.
C) in the market for fresh and frozen cranberries because it controls about 80 percent of the cranberry crop.
D) because it has lower costs of producing than other department stores due to economies of scale.