The single most important factor contributing to the increase in human life expectancy at birth that started at the beginning of the twentieth century was:

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Quizplus · Accepted Answer

Control of infectious diseases had a significant impact on the increase in human life expectancy at birth. Diseases such as smallpox, measles, and tuberculosis, which were major causes of death in the past, were brought under control through vaccination programs, improved sanitation, and antibiotics. This led to a significant decrease in infant and child mortality rates, contributing to the overall increase in life expectancy. While nutrition and medical care are also important factors, they were not as significant as the control of infectious diseases in the early twentieth century. The shift from rural to urban populations may have had an impact on other health outcomes such as access to healthcare, but did not directly contribute to the increase in life expectancy.

The Single Most Important Factor Contributing to the Increase in Human