<h3>
Answer:   D) It is affected by tides.</h3>
==========================================================
Explanation:
An estuary is where a river pours into the ocean. So that means fresh water mixes with salt water here. This allows us to rule out choices A and B. 
According to NOAA, their site says "Estuaries are one of the most productive ecosystems in the world, so there is a great diversity of animals and plants that live there". In other words, a lot of plants and animals live here, so we can rule out choice C. 
Choice D is the answer because tides do affect estuaries. This is simply because the ocean is pretty much right next to it, or attached to it. So it's expected that a high tide would cause the water level in an estuary to increase.
 
        
        
        
16,400 x (1 + 0.051)^20 = 
16400 x (1.051)^20 =
16400 x 2.70429659 = 
$44,350.46 
 
        
             
        
        
        
Answer:
2x + y = 2
Step-by-step explanation:
y = -2x + b
-4 = -2(3) + b
-4 = -6 + b
2 = b
y = -2x + 2 
2x + y = 2
 
        
             
        
        
        
Presently ratio is at 10:18 = 1.25
With 5 more girls & guys joining, ratio would change to 15:13 = 1.153846154
Therefore, the ratio of girls to boys would change rather not remain the same.
        
             
        
        
        
This transformation is called a rotation:-D