C) The fall of the United States embassy to revolutionary groups in Iran.
Explanation:
Letter choice C describes the Iran Hostage Crisis. This took place during the Carter Administration and was seen as one of his biggest failures as president.
Letters A and B represent events that happened before Carter took office. These events took place under President Nixon and resulted in distrust of the federal government and the Republican Party at this time.
Letter D also helped Carter, as he was only in politics for a few years before being elected President. Before this time, he was known as a modest peanut farmer from Georgia.
Fallout shelters are still someone in use but not for the purposes of nuclear fallout, only severe storms, etc. Th Interstate Highway System is the best choice from this list.
