Its A: the use of hydropower often changes the natural flow of water through an ecosystem 
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The answer you are looking for is A
 
        
                    
             
        
        
        
The resistance of a given conductor depends on its electrical resistivity ( ), its length(L) and its cross-sectional area (A), as follows:
), its length(L) and its cross-sectional area (A), as follows:

In this case, we have  ,
,  and
 and  . So, the total resistance of the wire with length of 138m is:
. So, the total resistance of the wire with length of 138m is:

 
        
             
        
        
        
4A. PE = MxGxH. (You can consider g as 9.8 / 10m/s as well)
 509 J = 12x10xH
 
 509 J = 120xH
 
 H = 509/120 
 
 H = 4.24 m
Hope u got the answer....pls rate the answer if it is helpful for u....and I'm sorry I could not understand B part so I didn't do it.
Thank you
 
        
             
        
        
        
Answer:
False
Explanation:
Paleobotany is the study of fossil plants.