Answer:
B
Explanation:
I took the Unit Test weeks ago, and I'm sure that it's right.
Hope this helped! :)
Ecological tipping points are the<span> points where environmental problems reach threshold level causing irreversible shifts in the behavior of natural systems. These are also called thresholds where the biodiversity changes.</span>

LOWA is the state which is bordered by the Mississippi River on the east , the Missouri River and the Big Sioux River on the western side .
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