The Iranian Revolution in 1979 had aimed an overthrowing the Iranian Shah from the Pahlavi dynasty and changing the state system into the theocratic republic. All that influenced the change in relations between Iran and America, in less than a year later, at the end of the same year in 1979, a hostage crisis took place in which fifty two US citizens were held as hostages for 444 days. The crisis was carried out on the side of Iranian students who embarked on the American embassy in Tehran, which led to an even worsening US-Iran relationship. This is otherwise the longest, hostage crisis in history.
The answer is: A.