Answer:
The correct answer is case control study. 
Explanation:
A study in which a comparison is made between the patients carrying the disease with the patients not carrying the disease is known as the case-control study. In the mentioned study, the one carrying the disease is termed as cases, and the one that does not possess the disease is termed as controls.  
This form of study is generally done to predict the association between the disease and the risk factor. In case-control studies, only observation is done as no attempt is made to change the course of the condition. The prime objective of the study is to predict the exposure of the risk elements for the individuals present in two groups, that is, controls and cases. This form of study is also called case-referent studies or retrospective studies.  
 
        
             
        
        
        
The correct answer is:  the   " phospholipid bilayer "  .
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              →   { which is hydrophobic (water-repellent) due to its waxy-like composition of many lipids.}.
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Hope this helps you!
         Best wishes!
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<span>This variation be justified by:
</span>Migration to an environment different from their birthplace, and adaptation to the available food, ultimately leading to speciation. because <span>birds use their beaks to eat.</span>.
        
                    
             
        
        
        
Since the formation of the San Andreas Fault system 25-30 million years ago, the juxtaposition of the Pacific and North American plates has formed many faults in California that accommodate lateral motion between the plates.
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