In 1979, the option d) Ayatollah Khomeini led a revolution to install an Islamic goverment in Iran.
This is known as the Iranian revolution. The government was replaced with an Islamic Republic. Before this revolution the Sha of Iran was the Persian monarch but he had to flee the country in January of 1979. The royal reign collapsed shortly after and the Islamic government was installed into power. In April of 1979 a national referendum made Iran an Islamic republic, a religious state with a theocratical-republican constitution where the Khomeini was the supreme leader.
