The Mongol Empire lasted only 100 years.
The Mali Empire lasted a little more than 300 years.
It is not A. I know because I got it wrong with this answer.
The Danes in the 9th and 10th Centuries, the Normans in 1066, the French in 1216 and 1326, and the Dutch in 1688
Carter created the United States Department of Education and United States Department of Energy, established a national energy policy and pursued civil service and social security reform.[1] In foreign affairs, Carter strongly emphasized human rights throughout his career. He signed the second round of the Strategic Arms Limitation Talks (SALT II) with the Soviet Union and, in an effort to end the Arab–Israeli conflict, initiated the Camp David Accords. With the Torrijos–Carter Treaties, he guaranteed the transfer of the Panama Canalto Panama in 1999. His administration also established official diplomatic relations with the People's Republic of China, while he signed the Taiwan Relations Act to define relations with Taiwan.
C- collapsing in Europe, the soviet economy was in shambles based on the fact the country was communist- a system of government and economics that has never worked when tried