Answer:
the correct option is B. over
The conditions being so bad? i might be wrong
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.
One of the major consequences of people migrating from the rural area to the city was that population density rose and living conditions in many cities became very poor.
