I believe its true but if not , my mistake
The answer should be C.
Hope this Helps! :)
Byzantium/Constantinople was conquered in 1451, but the empire continued to decline starting around the 18th or 19th centuries. It officially died in WWI. As for how long it was a major threat to Europe, the empire's prime was the 16th century, under Suleiman the Magnificent.
Because it was controlled by Russia who were communist, and the west was controlled by the US which was helping them develop their country again
