Final answer:
An example of a monopoly based on control of a key resource is the Paul Ecke Ranch monopoly on poinsettias.
Step-by-step explanation:
A monopoly based on control of a key resource refers to a situation where a single firm has exclusive control over a resource necessary for the production of a particular product or service. An example of such a monopoly is the Paul Ecke Ranch monopoly on poinsettias. The Paul Ecke Ranch has dominated the poinsettia market for decades, controlling a significant portion of the production and sale of poinsettias worldwide.