All of These Are Reasons a Pharmaceutical Company May Have

All of these are reasons a pharmaceutical company may have a monopoly on a life-saving drug EXCEPT

A) a patent providing legal protection against imitators.
B) economies of scale (large fixed costs) preventing two companies from being profitable.
C) control over a significant factor of production (such as a brilliant research scientist) .
D) a very low marginal cost of producing each additional pill.