I believe it is natural selection. Natural selection is when over a period of time, traits that are formed to help the organism survive, are passed to the next generation. For example, if there were two types of rabbits. One had black fur and the other was white. They both lived in the artic. The black furred rabbits are mostly eaten by predators because their black fur is easily seen against the ice and snow. Over a period of time, the black furred rabbit would die out. The next generation would mostly have white fur to help them survive.
        
             
        
        
        
Answer:
Krebs cycle
Explanation:
The Krebs cycle produces the CO2 that you breath out. This stage produces most of the energy ( 34 ATP molecules, compared to only 2 ATP for glycolysis and 2 ATP for Krebs cycle). 
 
        
             
        
        
        
Answer:
Scanning electron microscope.
Explanation:
It is scanning electron microscope because it is an electron microscope that produces image with three dimensional structure of the specimen by scanning the surface of the specimen using beam of electrons that is been focused causing an interaction between the electrons and atoms of the specimen which send signals that indicates information about the specimen.
 
        
             
        
        
        
Pistil is the correct answer! Hope it helps