The most common factor pushing people to leave their countries and emigrate to the United States was Economic Depression.
Many people came to the United States from China in the 1850s for better economic opportunities — often hoping to find gold in California. But few discovered gold, and most struggled to find opportunities elsewhere. As a result, many immigrants from China found that building the Transcontinental Railroad was one of the few ways they could earn money.
In 1882, the United States established its first laws to bar people from entering the country based on their national origin. Although many states had tried to pass laws restricting immigration from China in the late 1800s, those laws conflicted with a federal treaty between the United States and China. But after the United States renegotiated that treaty, it passed the Chinese Exclusion Act of 1882, which halted immigration from China to the United States for 10 years. For Chinese people who already lived in the United States, the act only increased violence against them and their communities across the country.
Answer:
B. Economic Depression