3. This list includes characteristics of life and work found in many large U. S. cities during the early 1900s. child labor tenement living high infant mortality rate dangerous working conditions Which factor led to an increase in the characteristics shown in the list? A. an increase in trade among North American countries B. an increase in the number of immigrants from southern and eastern Europe C. an increase in job opportunities along the western coast of the United States D. an increase in the standard of living among immigrants from northwestern Europe​