I think it is rarefaction. But im not sure
        
             
        
        
        
First blank -Same
Second blank-Neutral
        
             
        
        
        
Because they are coming from the ground and always safe
        
                    
             
        
        
        
Answer:
b. transfer of electron(s). 
Explanation:
An oxidation-reduction also called a redox reaction is a
chemical reaction in which electrons are transferred of between two species of reactants. It is a chemical reaction where the oxidation number of an atom, ion, or molecule, increases or decreases by losing or gaining electrons
 
        
             
        
        
        
Answer: petroleum 
because it is a fossil fuel like coal, and natural gas.