Answer:
D) Habitats for animals.
Explanation:
 It depends what the question means when it says 'the changing of the rivers'. I took it as the rivers are changing size and becoming more spread out. In that case, I chose habitats.
 The more water there is, the more habitat there is for sea life.
 All in all, the correct answer is D).
 
        
             
        
        
        
Answer: decrease to it’s carrying capacity
 
        
             
        
        
        
C they will adapt and eventually become a new species
        
                    
             
        
        
        
Oxygen is an abiotic factor that is beneficial by-product of primary production.
<u>Explanation:</u>
The non living parts of an ecosystem that mainly affects the living organisms in it are called as an abiotic factor. These can include soil, temperature, water, oxygen and sunlight. The major energy source in earth is Oxygen which is abiotic factor. 
It is very essential for the photosynthesis process to take place. Here, the plants converts water and carbon dioxide into oxygen and sugar. This becomes food for plants. Then these plants are eaten by animals. Thus oxygen is an important and beneficial by-product of photosynthesis. Oxygen is also very important for the survival of human beings. 
 
        
                    
             
        
        
        
The answer is invasive species.
Invasive species are species that are not native to specific ecosystem,
but they have a capability to spread widely through the ecosystem, This way
they can threaten native species of the ecosystem or cause
environmental harm. 
<span>After being introduced into the Black Sea, they greatly affect local
ecosystem. In the new area, they have no natural predators and are able to
spread. If they spread beyond the area they are introduced, they
become invasive species which can overgrow native biotopes and are
a great threat to the local biodiversity. This could lead to the extinction
of some native species.</span>