Answer:
The most important contributions is that the Byzantium Empire was able to preserve a lot of the knowledge and culture from the Roman and Greek Empires.
Things that could of let to population growth during the industrial revolution is that many people moved to the north to work in factories . By doing this everyone would move to the cities and increase the population of the north.
"make goths miserable" ??? Anyone can be miserable. and I guess you could say bullies? bullies make people miserable...
I believe its either A or C. Im thinking A more than C though
