Answer:
The above paragraphs describes that how salt- and fresh-water fish regulates their osmoregulation. Hence, the correct answer would be c. have adapted to deal with osmosis.
Osmosis is the process by which solvent's molecule move from region of low concentration (hypo-tonic) to the region of high concentration (hyper-tonic) through a semi-permeable membrane. 
In sea-water fishes, the body fluids are hypo-tonic to the surrounding water and thus water is kept moving out of their gills. In order to prevent the excess water loss they need to drink water constantly and excrete concentrated urine.
In contrast, fresh-water fishes body fluids are hyper-tonic to surrounding water and hence, water keeps entering in their body through gills. So, in order to prevent excess dilution they absorb salt from surrounding with the help of gills and also their bodies reabsorb salt from urine. 
 
        
                    
             
        
        
        
Answer:
A
Explanation:
I know this because I just took the test and got it right.
 
        
                    
             
        
        
        
Answer:
Study it under a microscope!
Explanation:
Any organisms in the pond water are more than likely very, very small! Microscopic, even;)
 
        
             
        
        
        
Explanation:
<u>Succession  </u>involves small scale changes within a community that occur repeatedly over the life of that community.
Ecological communities are highly dynamic- they gradually evolve. Typically their progression involves:
- colonizing species exploiting uninhabited areas (Primary succession)
- becoming a habitable and increasingly complex community
- there is increased diversity of organisms (Secondary)
Further Explanation:
The makeup of biological communities is crucial to defining Primary and Secondary succession; eventually, through changes in this makeup, a steady-state or equilibrium is reached called a climax community. While Primary succession starts off with the modification of a previously unoccupied area along with increasing variation; secondary succession begins after major disruption in the community such as fires, storms and flooding.
However, the process of becoming a climax community can be pretty complicated- it is very dependent on other factors like temperature and rainfall. Communities that experience rapid change, frequent major disruptions and even human intervention, are less likely to attain a stable equilibrium and may never become climax communities.  
Learn more about ecological succession at brainly.com/question/2456852
#LearnWithBrainly
 
        
             
        
        
        
Answer:
its the uracil
Explanation:
the four nitrogen bases in dna are adenine, guanine, thymine, and cystosine. In rna, thymine is imply replaced with uracil