Answer:
The Mississippians were a native American culture that inhabited the Mississipi River Valley and surrounding areas from 9th till 16th century. Their culture was unique in that they created Mounds, that is man-made hills, many of them are still existing today.
Answer:
The Zimmerman note and unrestricted submarine warfare by Germany
Explanation:
The Zimmermann Telegram was a note from German official to offer military alliance between Mexico and Germany. President Wilson understood the diplomatic relation and broke off the relation and decided to enter the WWI.
Germany was repeatedly attacking U.S. by submarine warfare in the Atlantic that killed ore than 120 U.S. citizens on May 7, 1915 that provoked outrage in the U.S. to participate in WWI.
Hence, the two reason are The Zimmerman note and unrestricted submarine warfare by Germany.
I think that the heat will not be able to maintain itself enough and the cold gases of the space could freeze earth and we would not be alive.
Hope this helps
