Pre-Columbian = pre-1492
Age of Exploration = 15th century - 18th century
Colonial Era = 16th century - 20th century
Revolutionary Period = 1764-1789
ANSWER
Two different species of mice migrated to the river from different directions.
EXPLANATION
Solved scientifically in my head.
The answers are
6._ Harder
7._Best
8._Least Exited
These are the answers in my opinion.<span />
