content area Part 1 The De Beers Company of South Africa has faced limited competition in the market for diamonds. Part 2 What barrier has kept new firms from entering the market for diamonds? Part 3 The De Beers Company of South Africa Part 4 A. has had almost exclusive ownership of diamond mines, which is a key input. B. has had lower long-run average costs than competitors. C. has enjoyed economies of scope from producing multiple types of products. D. has had a patent on diamonds. E. has been able to convince customers that its brand of diamonds has extra value