1 the atmosphere because gas is everywhere. 
        
                    
             
        
        
        
Its organism because it is one single thing.  
        
                    
             
        
        
        
Answer:
Electron microscope would be used for if, 
C) details of cell structures needed to be distinguished.
Explanation:
- The general principal of electron microscopy is analogous to light microscopy except that it uses electrons to analyse the specimen instead of light.
- Electron microscopy focuses a beam of electron on the target sample and records the difference in absorption by different surfaces.
- Electron microscopy is used to get the detailed structure of cells and surface features of various viruses and bacteria.
- However, it is not possible to view living biological samples through electron microscope because high velocity electron have immense energy to kill living cells.
- These samples are thus, fixed and then viewed.
 
        
             
        
        
        
Explanation:
Spillover infection, also known as pathogen spillover and spillover event, occurs when a reservoir population with a high pathogen prevalence comes into contact with a novel host population. The pathogen is transmitted from the reservoir population and may or may not be transmitted within the host population.