Answer:
The Great Plains had rivers which allowed various Native American tribes to camp along these rivers while they were following the buffalo. So again, the geography of the area provided this availability of food and places to stay and feed and water their horses.
A net population decline resulting from an "excess of deaths over births".
Option: A
<u>Explanation</u>:
Demographic transition is a shift from higher to lower level of fertility and mortality.Rapid development in industrialization and urbanization in 
century resulted into enormous population growth. But decline in early 
century covered many reasons like consequences of two calamitous wars, where Europe suffered large population declination due to battle death and civilian causalities in World War I and II. Hence the acceleration of population growth in 19th century but downfall in 20th is also considered as balance.
They re both close to the magnetic poles and during summer the sun never sets and during winter it barely rises.
The printing press did this
C. the rocks closest to a continent are younger
