Well could be disease's and violence speaking they had a war.
C. Is a Factual Statement
This one is tricky, because scientific law can explain an observation, or be used to make a prediction, but I believe that C. is the most correct of the 4 answers.
Walter Mondale lost to Ronald Reagan by a landslide.
I assume your talking about the HUNS... When the empire split in two the east had more gold and more resources and the dying west had to suffer all the barbarian attacks like the huns... The East quite simply was more prepared and had more walls and guards to defend their border also the Eastern Empire had the river danube north of them which helped deflect the Hunnic invasions and other barbarian invasion more west...