An example could be oil (olive, almond)
        
             
        
        
        
Answer:
1. A massive star depletes its nuclear fuel; gravity overpowers the star; supernova occurs; core of star collapses
2. black hole; gravitational pull
3. The center of the Milky Way
Explanation:
 
        
             
        
        
        
The answer is a. the troposphere