Answer:
D. A sharp rise in immigration.
Step-by-step explanation:
The so-called Gilded Age in the history of the United States of America, is the period after the War of Secession and Reconstruction, from the 1870s to the 1890s, when the country experienced an economic, industrial and demographic expansion without precedents, especially in the north and west but also a great social conflict and great inequalities, economic and social.
American wages, especially for skilled workers, were much higher than in Europe, which attracted millions of immigrants. The increase in industrialization produced an increase in business profits and also in real wages that grew by 48% from 1880 to 1890, which did not prevent it from being a time of poverty for those who could not find work and for European immigrants. There was the Great Depression of 1873, two major depressions at the national level along with two banking panics (the panic of 1873 and the panic of 1893).