The human respiratory system is basically the circulation of the body. the lungs which produces air/oxygen that cycles around the body which produces oxygen.
        
             
        
        
        
The correct answer is Stimulus.
A thing or an event that provokes a specific functional response in an organ or tissue of an organism is called as stimulus. It can be anything like heat, light, water, chemical et cetera. Any stimulus when encountered by the organism produces response in reference with the stimulus generated by the external environment or other organism.
 
        
                    
             
        
        
        
Answer:
The rate of photosynthesis is at a maximum over a narrow range of light intensities.
Explanation:
Light provides the energy required to drive the process of photosynthesis. Starting from a low light intensity, the rate of photosynthesis increases as intensity increases.  Hopefully helps ig
 
        
             
        
        
        
The function of Mitochondria is in the generation of metabolic energy in eukaryotic cells. Mitochondria are responsible for most of the useful energy derived from carbohydrates and fatty acids. Assembly of Mitochondria thus involves protein encoded by their own genomes and translated within the organelle.
        
             
        
        
        
I don’t know why they make everyone type more than 20 characters but B sounds like the most reasonable answer.