Answer:
i think d
Explanation:
<u><em>hoped i helped</em></u>
 
        
                    
             
        
        
        
Answer:
An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. The first contact that an organism has with a particular antigen will result in the production of effector T and B cells which are activated cells that defend against the pathogen.
Explanation:
 
        
             
        
        
        
In meiosis, the chromosome pairs do the crossing over where there is an exchange of genetic material between them and because of it the
chromatids held together by the centromere are no longer the same.
        
             
        
        
        
The correct answer is B. Thymus gland: enables immature lymphocytes to mature into T cells
        
                    
             
        
        
        
Answer and Explanation: The excretory system helps the respiratory system by getting rid of carbon dioxide. The respiratory system helps the excretory system by getting rid of CO2 from the body. They both need each other and if one or the other did not exist, we might've not been able to survive. Tis demonstrates how vital they are for the human body.