Question

the main factors contributing to the decline in death rate in 20th century were​

Answer 1

During the first half of the century, changes in the ability to avoid and withstand infectious diseases were the prime factors in reducing mortality. Infectious diseases were the leading cause of death in 1900, accounting for 32 percent of deaths. Pneumonia and influenza were the biggest killers.

Answer 2

Answer:

• Throughout the 20th century in the developed world, the leading causes of death transitioned from infectious diseases such as influenza, to degenerative diseases such as cancer or diabetes.
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