Answer:
C) from nearly 40 million in 1870 to nearly 80 million in 1900.
Step-by-step explanation:
During the Gilded Age, the population of the United States rose from nearly 40 million in 1870 to nearly 80 million in 1900. The doubling of the population in only 30 years was a problem that the government was ineffective in fixing. Jobs were not as easily available as they had been in the past. Moreover, the influx of immigrants was massive, and this meant that many of them struggled to make a living upon arrival. The Gilded Age, therefore, was a period of time with many social and economic problems, particularly in urban areas.