Answer:
Rock
Explanation:
Let's calculate the density of each object:
Rock:
 
 
Pencil:

Therefore the rock is denser. 
 
        
             
        
        
        
Fossil fuels and unnatural energy sources still dominate in the US, this influences many problems including global warming, climate change, and pollution. Burning fossil fuels is also a problem to human health. And unnatural resources won’t be there forever whereas, renewable sources could last a long time.