His most challenging and unresolved problem was the takeover of the U.S. Embassy in Tehran, Iran in 1978 by Islamic fundamentalists and the taking of more than 40 American hostages. Carter was unable to secure their release during his presidency. The were released once Ronald Reagan took office.
B - Some communities closed their schools rather than to integrate.
While some in the the south did not want to integrate their schools, some communities refused (but not most) and they figured out plans to delay integration, transfer students to different schools and close others.
Vasco da Gama was a Portuguese explorer who, in 1498, became the first European to land on the Indian coast