The doctrine of popular sovereignty was used. That meant that people in those states could choose to vote to support slavery and since they were majority then slavery would be permitted. There were even states that were at first non-slave states but then things changed and they voted to introduce slavery into the state and people voted for this and supported this.
        
             
        
        
        
Answer:
At the December solstice, Earth is positioned in its orbit so that the sun stays below the North Pole horizon. As seen from 23 1/2 degrees south of the equator, at the imaginary line encircling the globe known as the Tropic of Capricorn, the sun shines directly overhead at noon.
Explanation:
 
        
             
        
        
        
Answer:
The most obvious way was through open rebellion. In 73-71 BC the gladiator Spartacus famously led an uprising of thousands of slaves in central Italy, formed an army that defeated several Roman legions, and at one point threatened Rome itself.
        
             
        
        
        
Answer: Region C, Region D
The Mound Builders were inhabitants of North America who built various styles of mounds mostly for religious and burial purposes, 5000 years ago. Most lived in the regions of the Great Lakes, the Ohio River Valley, and the Mississippi River valley,
Based on the map presented, The Mound Builders primarily lived in regions C and D where Mississippi and Ohio Valley are located.