A natural monopoly usually arises when

a. there are diseconomies of scale in an industry.

b. the government allows unrestricted access to a market.

c. there are large economies of scale relative to the industry's demand.

d. companies band together to form a cartel.

The correct option is: c. there are large economies of scale relative to the industry's demand.

Explanation:

A natural monopoly is a classification of monopoly which arises due to the greatest price of start-up or adequate economies of scale handle the market in a particular industry. The characteristic of a natural monopoly is that it has a complex structure of cost. Furthermore, it has a higher fixed price for goods that do not depend on results, but the marginal price of the manufacturing of goods is consistent and very low.