Answer:
True
Explanation:
A monopoly is when there's only one firm operating in an industry.
If De Beers Diamond company advertises for all the diamonds, it shows that it has some degree of ownership over the other diamonds in the industry.
Other characteristics of a monopoly :
1. They set the prices of their goods and services.
2. There are high barriers to entry of firms
3. Price is usually greater than marginal cost.
I hope my answer helps you
