Answer:
A. Populations were separated through geographical isolation.
Explanation:
 
        
             
        
        
        
C. because stimuli is how your body responds to something, and in this case, someone's heart rate increases WHEN their blood oxygen drop. Do you see how it responds? ;-)
        
             
        
        
        
Answer:
It is made up of protons and neutrons
 
        
                    
             
        
        
        
Im pretty sure its the genus
        
             
        
        
        
Answer:
The correct sequence of muscle contraction from first to last is given below
Explanation:
step 1  myosin head interacts with actin
step 2 ATP binds to myosin head 
step 3  ATP is converted to ADP and Pi
step 4  ADP and pi are released from myosin 
step 5  Myosin head pivots in the power stroke 
step 6  Myosin head is cocked back.