The antibodies to the HIV virus may take up to three months to appear in the blood of the infected person. 
Therefore, the second blood test is necessary three months after a person thinks that he/she has been exposed to HIV to check the presence of these antibodies and confirm whether the person is infected or not.
        
                    
             
        
        
        
Answer(nasal cavity, trachea, bronchi and bronchioles
Explanation:
 
        
             
        
        
        
Answer:
I would go to option C 
Explanation:
Autotrophs are organisms that can produce their own food, using materials from inorganic sources. Option C matches this definition and process. 
Stay safe and Merry Christmas! :) 
 
        
                    
             
        
        
        
D) when cells are express different genes
        
                    
             
        
        
        
I’m pretty sure it’s c but I’d pick d