A-The Amazon acts as more of a barrier to movement
b- The Amazon is much harder to get to
c- The Amazon is surrounded by farmlands
Explanation:
The Amazon river has surroundings which are largely underdeveloped with large amount of plant life. They also inhabit lots of animal life too.The surroundings are hard to get to due to poor road network.
The Mississippi River however is found in a more developed industrial area and lacks a dense plant population with good road networks.
The friend is incorrect as all stars move in the sky and rotate around the northern star meaning it was the same constellation even if it was in a different location