After having a monopoly in the diamond market for many years, by 2000 the De Beers company faced competition from other companies. To maintain its market share, De Beers

A) lowered the prices of its diamonds to make the market appear less profitable to potential competitors.
B) began buying so-called "blood diamonds" in order to keep these diamonds out of the control of other diamond companies.
C) bought diamond mines in Canada and Russia that had been its competitors.
D) adopted a strategy of differentiating its diamonds. Each of its diamonds is now marked with a microscopic brand.

D