Answer: 
D. Feel-good/pleasure 
I hope I helped!
        
             
        
        
        
Explanation:
Significance. The cycle's importance is based on the prevention of lactic acidosis in the muscle under anaerobic conditions. However, normally, before this happens, the lactic acid is moved out of the muscles and into the liver. The cycle is also important in producing ATP, an energy source, during muscle activity.
 
        
             
        
        
        
Theories are a collection of scientific data that is generally accepted and reproducible. Theories are a result from several repeated experiments, but theories are not based on a single hypothesis. Several hypotheses are tested and appraised to become a well accepted theory. Theories may also be revised over time and can predict what may happen in the future. On the other hand, theories are not proven facts.
        
                    
             
        
        
        
The free nerve endings
can detect pain, temperature, itch and hair movement. Merkel's disks can detect pressure, position and static touch features. Pacinian corpuscles are sensitive to vibration while Meissner's corpuscles are sensitive to light and touch.
        
                    
             
        
        
        
Chemical bond is the right awnser