D doesnt fix the sentence because the period in this case breaks the sentence apart but into an incomplete and complete sentence. 
"Sometimes he lets us play them." isnt a complete sentence which is a period isnt the way to make this run on sentence better.
        
             
        
        
        
Answer: What happens if you swallow gum?
Explanation: Tell me! BECAUSE I ATE GUM ON ACCIDENT!!!!
 
        
             
        
        
        
Answer:
soil erosion 
Explanation:
because soil can't erosion 
 
        
                    
             
        
        
        
Answer:
Your song is very good!!!