Well, It's either OCD or PTSD... Depending on what the person has gone through in the past, it could be PTSD, PTSD would be caused by being traumatized by something, Like if I got robbed, i would check if my doors are locked. 
        
                    
             
        
        
        
Answer:
B - Protons and Neutrons
Explanation:
This is because the electrons are in the electron cloud.
 
        
                    
             
        
        
        
Arteriosclerosis: It's when your arteries get hard. 
Atherosclerosis: It's the medical term for when your arteries are clogged with cholesterol.
        
                    
             
        
        
        
Answer:
a discovery by a human being
Explanation:
The correct answer would be a discovery by human being.
Penicillin existed in nature and was only discovered, albeit accidentally, by Alexander Fleming. 
It is different from<u> technological innovation because the latter requires the synthesis of products that are not in existence already or improvement on a product that has been created before</u>.
Discovery is also different from advancement in technology. <u>The latter refers to the process of inventing, innovating, and spreading technological processes in society.</u>
Discoveries are usually natural and are not in any way an invention. However, advancement in technology can aid discoveries.