Answer: Hypothalamus 
The brain coordinates the physical changes that occur during puberty and the hypothalamus plays an especially important role in this process.
Explanation:
Since the hypothalamus controls the secretion of hormones from the pituitary gland, and the pituitary gland, also known as master gland, controls the activities of all other glands like the following:
- gonads (ovaries and testes), responsible for producing many of the sex hormones and hence, development of sexual characterictics
- thyroid, responsible for producing thyroxine, responsible for body metabolism and development.
Thus, hypothalamus plays important role in puberty
 
        
             
        
        
        
A.Structure relates to function, is the answer
        
             
        
        
        
Answer: They represent different concepts
 
        
                    
             
        
        
        
The Mohs scale measures D, a mineral's hardness.