The great ancient civilizations flourished around river valleys because the rivers produce rich fertile soil and a supply of water for irrigation of crops and human consumption. This allows for the agricultural production to be greater and it can sustain more people.
Between 1870 and 1900, unprecedented numbers of Europeans immigrated to other countries.
So, your answer is option C. Immigrated to other countries.
Hope this helps!
<span>c.to wake up African-Americans and give them a sense of their place in history</span>
