The simplest way for a monopoly to arise is for a single firm to A. decrease its price below its competitors' prices. B. own a key resource. C. make pricing decisions jointly with other firms. D. decrease production to increase demand for its product.

The correct answer is B. The simplest way for a monopoly to arise is for a single firm to own a key resource.

Explanation:

A key resource is defined as any input, element or material that, autonomously or through a composition with other materials, constitutes an element or product that is totally distinctive from that of the competition, both in its quality and in its specific details and compounds, making it unique and unrepeatable, and predisposing the demand to buy it.

When a company succeeds in obtaining or creating a key resource, it captures the demand for it and, through marketing and organizational management, can impose a monopoly on the product and its associated products.