For Years the Paul Ecke Ranch Had a Monopoly on Poinsettias.What

For years the Paul Ecke Ranch had a monopoly on poinsettias.What was the reason for the monopoly the Ranch had on poinsettia sales?

A) The Paul Ecke Ranch was granted a public franchise which made it the sole legal provider of poinsettias.
B) Paul Ecke discovered a technique for growing poinsettias that had more leaves and were more colorful than other poinsettias.
C) The Paul Ecke Ranch was granted a patent that gave it the exclusive right to produce and sell poinsettias.
D) The Paul Ecke Ranch was able to take advantage of network externalities in supplying poinsettias.