Because of the discovery of gold in San Francisco in 1848, many people began moving west to search for wealth and fame. The United States was discovering many things underground...gold, silver, and oil. These were some of the natural resources the United States had at the end of the 1800s.
Masacre de Nanjing donde las fuerzas imperiales japonesas ejecutaron deliberadamente a civiles chinos. Se estima que entre 50.000 y 300.000 personas murieron durante la masacre.
I believe the answer is D. Hope this helps.