I think B is the correct answer.  Answer choices C & D are about dolphins, but they do not have anything related to negative effects surrounding human and dolphin interaction.  A, on the other hand, may seem like a good choice, but then again, the answer is too vague.
        
             
        
        
        
Answer:
Intestinal blood flow is critical for digestion, as well as a key element of overall well-being. The O2 consumption of the small intestine is more  controlled than is the large. 
Explanation:
 
        
             
        
        
        
the answer is four hope this helps :)