Answer:
b
Explanation:
 I'm not sure about the answer
 
        
             
        
        
        
Into the middle of a narrative without introduction
 
        
             
        
        
        
A, The river is constantly changing. I did this last year so I know what the answer is. Fickle means changing frequently or in my term, stubborn. In his point of view, the river has a mind of its own and changes often. Which he described as "fickle." It may be hard for Twain to pilot a steamboat, if the river is constantly changing.
        
             
        
        
        
The answer is not complex sentence it is compound sentence