Answer:
Considering the boys' situation, the boys live in the rural areas of one of the western United States, e.g. California.
Explanation:
Hantavirus is spread by rodents and is most common in rural areas of the western United States during the spring and summer months.  Hantavirus pulmonary syndrome also occurs in South America (especially in Argentina, Chile, Uruguay, Paraguay, Brazil, and Bolivia).  Hantavirus cases have also occurred in Canada and some parts of Asia, where they reportedly caused kidney disorders rather than lung problems.
 
        
             
        
        
        
Out of the choices given, the mechanisms that drives evolution is natural selection. The correct answer is B, natural selection. 
        
                    
             
        
        
        
Answer:
physical, or biological anthropology.
Explanation:
When there is a need to study human kind   through the X-ray of  relationships between human biology, its cultural diversity, and  evolution ,the aspect anthropology for this is Biological anthropology.
Therefore biological anthropology is concerned about how the interaction between the cultural diversity and biological process results in the  adaptations of mankind to different  environments.The influence of these on growth, behaviours, existence.
The primary focus of biological anthropologists is to study in details the concept of  ,mechanism of  variation,  adaptation.and how these lead to evolution and origin of mankind.
Sequel to this ,most evidences for this concept are obtained from the study of fossil materials,study of other related primates to man, and components of functional biology and genetics. 
 
        
             
        
        
        
Answer:
The organs of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. The accessory digestive structures include the teeth, tongue, salivary glands, liver, pancreas, and gallbladder.
Explanation:
 
        
             
        
        
        
Crystallization
This is a technique commonly done by chemists to purify compounds. During crystallization, an impure,solid compound is dissolved with a hot solvent. In the container the impurities and the needed compound move freely. When the solution cools down, the solvent can cannot hold all the solutes. Each solute will form a crystal. Therefore each crystal is made of only one molecule. Once it cools down if will be placed in a cold bath to complete the crystallization.