TOEFL Reading: ETS-TOEFL阅读机经 - M43IIA5_30AJFJWTL$

According to paragraph 5, what effect did the epidemic-disease cycle have on population during the eighteenth century A. Childhood diseases kept population growth rates from rising even higher. B. Periodic epidemics caused population growth rates to rise and fall in cycles. C. The effect varied by area, with urban populations more affected by disease than rural areas. D. Fewer childhood deaths from disease led to an increased number of children in the current and future generations.