Why Was Life Expectancy in Early Cities Shorter Than Among

Why was life expectancy in early cities shorter than among nomadic hunter-gatherer peoples?

A) The carbohydrate-rich diet was less nutritious,and cramped housing in the cities resulted in increased exposure to infectious diseases.
B) The success of the cities and their stored supplies of food attracted attack from outside,chiefly by nomadic peoples.
C) The process of in-home burial led to an increase in contagious disease.
D) Food was often portioned out according to social class and sex,resulting in an inadequate diet for women and the poor.
E) People in early cities exercised less and ate more than people who lived in traditional hunter-gatherer societies.