Answer:
I would say A, the other options dont make sense.
It may be because of environmental problems like droughts or cold weather. It could be because of poor farming. Religous problems or just econimic problems that led to people moving to find another place to stay.
Ancient Egypt: Social Classes. The Ancient Egyptian Social Pyramid has social groups such as the pharaoh, vizier, high priests and nobles, priests, engineers, doctors, scribes, craftsmen, slaves and farmers.
In the social pyramid of ancient Egypt the pharaoh and those associated with divinity were at the top, and servants and slaves made up the bottom. The Egyptians also elevated some human beings to gods. Their leaders, called pharaohs, were believed to be gods in human form.
At the top of the social pyramid was the pharaoh with the government officials, nobles and priests below him/her. The third tier consisted of the scribes and soldiers with the middle class in the fourth level. Peasants were the fifth tier of society with slaves making up the lowest social class.
hope this helps