Why Does Spain Have an Absolute Advantage in Growing Saffron

Why does Spain have an absolute advantage in growing saffron?

A) Spain has some of the lowest labour rates in the world so the time-consuming harvesting process is less expensive.
B) Treaties limit which country can produce saffron.
C) The spice is relatively inexpensive so other countries are not interested in growing it.
D) Saffron thrives in Spain's climate and soil but does not do as well elsewhere.