Answer: "estuaries" .
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B)Railroads - more cities could access railroads and increase trade. was built more in the 1800s.Canals was a short-lived era. [ Railroads beginning in the late 1830s and early 1840s were built because they were faster and more reliable than Canals which were often destroyed by washouts of the banks and floods destroyed many canals. The first transcontinental was completed in 1869, by 1900 there<span>were 15 transcontinental railroads. ]</span>
The Mayans lived in what we now call Mexico and South America.
World War 1 or First World War was known as the Great War or "The war to end all wars", before the beginning of the Second World War.
The principal countries involved in this war were Russia, France, Britain, Italy and the United States of America in one side, and Germany, Austria-Hungary, and Turkey on the other side, forming two opposed alliances: The Allies and the Central Powers.
This war began because of a Serbian nationalist, who killed Archduke Ferdinand, heir of the Austrian throne. Because of this act of terrorism, a great war started, and that come to be known as the major European conflict in a hundred thousand years.