The answer is C. 
The author provides different facts. For instance, "Unlike normal rocks, they have trails etched behind them as if they have traveled across the sand. Some trails are only a few feet. Some trails are over a half a mile long." Is an example of a fact. 
Another example includes, "Some rocks seem to roll as they move forward. Some take unexplainable routes. Large ones have traveled past small ones that have stayed still."
        
                    
             
        
        
        
only b is the right answer
tho i dont understand the last option
 
        
                    
             
        
        
        
Answer:
Its D you have a pfp that makes sense it's hard
 
        
                    
             
        
        
        
Answer: Because if you are uncertain of what's happening then you don't know how to deal with the situation. So in order to compensate for that not knowing, you take a risk.