I would select B or C as the answer because i have no idea what the other ones are :)
        
                    
             
        
        
        
The epiglottis is a flap in the back of your tongue that prevents food from entering the larynx. When your mouth is closed, the epiglottis is in place and blocks the larynx opening. If your mouth is open, the flap lifts and the larynx is no longer blocked so you can breathe. This is why it's important to not chew with your mouth open... if you do, then food can go down the larynx by mistake.
        
             
        
        
        
That would be A. 
Cells have specific receptors for different hormones that allow the intake of them.
        
                    
             
        
        
        
Answer:
This is the digestive system.
Explanation:
We can tell that this is the digestive system because we can see #1: The stomach, #2: The small intestine, #3: The large intestine, and #4: The liver. Hope this helped!
 
        
             
        
        
        
The statements above are true;
In a host-versus-graft rejection the recipient's immune system recognizes the donor's tissue as foreign and rejects the transplant. On the other hand, in a graft-versus-host rejection, the donor tissue recognizes the recipient's tissue as foreign and the transplant rejects the recipient, causing destruction of the recipient's tissue and possibly death. Its important also to note that there are two types of rejection, the acute rejection, where the rejection of transplanted tissue that occurs several weeks after transplant. it is delayed hypersensitivity reaction, and the chronic rejection is a rejection of transplanted tissue that can occur at a late time. Immune complexes form in the arteries supplying the graft, choking off the blood supply and the tissue is rejected.