18. a dam generates electricity from water flowing downhill and is an example of how systems… a. violate the 2nd law of thermodynamics b. take advantage of energy flow from low to high c. violate the 3rd law of thermodynamics d. take advantage of energy flow from high to low

Hello!! 

When a dam generates electricity, it is doing so, ultimately from The second Law of Thermodynamics, taking advantage of energy flow from high to low.

So we can see the best choice here would be D. 
To take advantage of energy flow from high to low. 

Hope this helps! Any questions, please feel free to ask! Thank you kindly!

Ido not know at all

No bc a lot of things r still theories n unproven