Final answer:
Americans tend to see historical grievances as the root of poor relations with Iran.
Step-by-step explanation:
The root of poor relations between the United States and Iran is seen by many Americans as Option 4: Historical grievances. The history of US-Iran relations is complex, with several key events shaping the mutual distrust between the two countries.
A major turning point was the ousting of Iranian Prime Minister Mohammad Mossadegh in 1953, which was supported by the United States and seen by Iranians as interference in their affairs. Additionally, the US support for the authoritarian regime of the Shah and its involvement in the 1979 Iranian Revolution further strained relations.