Answer:
A. control a resource that is essential in the production process.
Explanation:
When the crucial resource is required to make a product, then the restrictions on such resource would not allow, many people to enter in such business.
Also that the resources will be restricted in some or other manner, its price will increase accordingly the cost of producing such article would also increase.
As the cost of production will increase only producers with a high budget and resources in terms of finance will chose it.
