The answer to this question is "repairing old appliances"
        
             
        
        
        
I think Earth’s atmosphere plus atmosphere. So, 23+48=71. So, the answer is A
        
             
        
        
        
Answer:
Homeostatic control mechanisms have at least three interdependent components: a receptor, integrating center, and effector. ... The integrating center, generally a region of the brain called the hypothalamus, signals an effector (e.g. muscles or an organ ) to respond to the stimuli.
Explanation:
 
        
             
        
        
        
A chemical bond to form in a chemical compound must be formed by two or more atoms attracted to one another.
        
                    
             
        
        
        
I hope this can help some.