Mohammad Reza Pahlavi Was the Shah of Iran, His Reign

Mohammad Reza Pahlavi was the Shah of Iran, his reign beginning in 1941. In the late 1970s, more than 10 percent of the people of Iran marched the streets in anti Shah demonstrations. As a result, the Shah left Iran for exile, and the Islamic Republic of Iran was established. What term best describes the actions of the Iranian citizens?

A) insurgency
B) revolution
C) coup d'etat
D) uprising