Birds because they spread seeds
        
             
        
        
        
An independent variable is a variable which change is not affected by that of another variable. By process of elimination you can take out B and C. An independent variable can also change so that takes out A. That leaves D.
        
                    
             
        
        
        
The fact that gravity exists as it can be repeatedly tested and verified
        
                    
             
        
        
        
Answer:
I guess it is a Secondary Succession.
Explanation:
Secondary succession is the series of community changes which take place on a previously colonized, but disturbed or damaged habitat. Examples include areas which have been cleared of existing vegetation.
 
        
                    
             
        
        
        
<span>Answer: Biodiversity</span>
The suppression of forest fires causes a decrease in biodiversity because
some habitats require exposure to fire. Most ecosystems of savanna, chaparral
and coniferous forests have developed with fire as an essential contributor to habitat’s vigor
and regeneration. 
Additionally, wildfire suppression eliminates plant species
in fire-affected environments that require fire to germinate, established, or to
reproduce. Also, animals that depend on these plants will be affected too.