I could really use some help on this, big time. Thank you. Really appreciated.

Answer:
I thinks it's B
Explanation:
Because it's what dams do.
It's not D because it caused people to relocate, it's not C because that doesn't make sense.
Answer:
B
Explanation:
seems most logistical considering that is what dams are made to do control flows of water and or stop the flow of it