Answer :
"D. With no centralized government to impose order, lawlessness increased" is a good description of how life changed initially, but soon local governments took control.
The answer is:
D. With no centralized government to impose order, lawlessness increased.
After the fall of the Roman Empire, many territories were left with no law and no law enforcers, this meant that the people were on their own and left room for robberies and other crimes to happen.