Zoroastrianism Was the Dominant World Religion During the Persian Empires

Zoroastrianism was the dominant world religion during the Persian empires (559 BC to 651 AC) and was thus the most powerful world religion at the time of Jesus. It is still practiced worldwide, especially in Iran and India. Within these two countries, the religion's members share a set of beliefs that set them apart from others who reside in the country. Believers in this religion would be classified as a(n) :

A) classless society.
B) subculture.
C) national reference group.
D) transformational group.
E) opinion group.