The most accurate response to explain why the Iranian Revolution had a major impact on the politics of Arab countries is: The Iranian Revolution demonstrated that it was possible to base a government on religion.
This event marked a significant shift in political ideology in the Middle East, showcasing a successful example of a theocratic governance model, which inspired various religious movements across the region. The revolution demonstrated that it was feasible to reject secularism and Western influence in favor of an Islamic state, leading to increased interest in political Islam among various groups in Arab states.
While Iranian ideas about Islam did spread throughout the Middle East, the fundamental takeaway of the Iranian Revolution was its demonstration of how a government could function based on religious principles, thus resonating with numerous groups seeking to establish similar systems within their own countries.
The other responses are not accurate in the context of the Iranian Revolution's impact. Iran is not an Arab country, and the revolution did not involve the invasion of neighboring territories.