Answer: B. an increase in the number of immigrants from southern and eastern Europe.
Step-by-step explanation:
From 1880 to 1914, it is estimated that over 20 million people immigrated to the U.S. from southern and eastern Europe. They were escaping persecution and looking for a better life.
These people needed jobs to survive and so would try to get as many people as possible to be employed including children so that more of the family would earn money. The conditions that they worked in was quite dangerous but they would still go to work because they needed an income.