Answer:
Simple epithelium is a single layer of cells with every cell in direct contact with the basement membrane that separates it from the underlying connective tissue. In general, it is found where absorption and filtration occur. The thinness of the epithelial barrier facilitates these processes.
 
        
             
        
        
        
Answer:
Your answer would be A. GENES
Explanation:
 
        
             
        
        
        
Caleb’s immune system will have the experience of getting rid of this antigen and know exactly what to do to overcome it efficiently.