Answer:
Because if the 4-year-old child passes out from holding his breath, he will immediately begin breathing again, keeping him alive.
 
        
             
        
        
        
Grass and stuff they are herbivores 
 
        
             
        
        
        
Answer:
chromosomes
Explanation:
Thread-like structures that are found in the nucleus of a cell that contains all DNA. Each chromosome is made of protein and a single molecule of DNA. Human cell nucleus contains 46 chromosomes or 23 pairs. Half of these chromosomes come from one parent and half come from the other parent.
 
        
             
        
        
        
Answer: digestive is the correct answer
 
        
                    
             
        
        
        
18mg for a 19-50 year old adult female.