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what is infant mortality rate?

Infant mortality is the death of an infant before his or her first birthday. The infant mortality rate is the number of infant deaths for every 1,000 live births. ... In 2019, the infant mortality rate in the United States was 5.6 deaths per 1,000 live births.

industry had made the u.s. the richest nation in the world at this time. the second industrial revolution caused growth in industry and transportation, which allowed increased trade between nations. click to let others know, how is it

the answer is:

c. economic output