Which of the following is the best example of a natural monopoly?

A. A pharmaceutical company has a patent that prevents any competitors from competing with it.

B. A movie theater prohibits patrons from bringing in their own food or drinks and charges high prices at their snack bar

C. The hospital in a small town where the daily census of patients averages about 70% of capacity

D. Owning all of the orange properties and building hotels on them.