A metamorphic rock is a type of rock which has been changed by extreme heat and pressure.  so must be option D
        
             
        
        
        
Answer:
The right response is "Natural killer".
Explanation:
- Natural killer cells constitute immune cells which could also identify and ultimately destroy distressed or damaged cells. This might also target cancerous as well as tumors. 
- That alone reduces inflammation that lyses this same cell cycle rather than being amongst the very first cells towards prepare an inflammatory system, and even more so towards virus cells, participating including its destruction.
 
        
             
        
        
        
In scientific notation, the value of the speed of light in a vacuum
 will be written as 2.995 * 10^8. When this value is represented in the form of
 a * 10^b, then, a = 2.995 and b = 8.
The value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. In this case, the scientific notation will be written as 3 *10^8.
        
                    
             
        
        
        
Explanation:
Noble gases have a full outer energy level and are inactive. These atoms are considered inert. 
Hope this helps 
Good Luck