Since the options are not given the question is incomplete.
Which of the following is not a health related component of fitness?
A). Body composition
B). Flexibility
C). Muscular strength and endurance
D). Stress management
Answer: Stress management
Explanation:
Fitness in terms of health is associated with physical fitness. The physical fitness involves the dynamics of working and functioning of the physical body. This is associated with composition of the body, body shape, weight regulation, flexibility, strength and endurance required to perform a task and other physical attributes.
The stress management is related with mental fitness. It helps in reducing mental stress and improving thinking abilities, which can help in overcoming stress. 
 
        
             
        
        
        
The answer is C. Cardiovascular 
best of luck :)
 
        
                    
             
        
        
        
Triglycerides, cholesterol and other essential fatty acids—the scientific term for fats<span>the </span>body<span> can't make on its own—store energy, insulate us and protect our vital organs. They act as messengers, helping proteins </span>do<span> their jobs. Hope this helps :)</span>
        
                    
             
        
        
        
A RN Nurse would be better and quicker and a good start. Many schools are forwarding that position and beginning to make classes about it, as the nurse job is the future. 
That's my opinion, take it from a Fire Fighter and soon to be EMT.