Susan asked her roommate to lower the radio because she was trying to study. Her roommate had turned the radio up originally from a volume level of 14 to 15, which was just enough for Susan to detect. Susan's reaction relates to the concept of:

The correct answer would be south africa

Ongoing civil wars western roman empire finally collapsed476 c.e. romulus, the last of theroman  emperors in  the west, was overthrown by the germanic leader odoacer, who became the first barbarian to rule in rome. the order that the  roman empire  had brought towestern  europe for 1000 years was no more.

The correct answer is "bantu".