The correct version of these two sentences when combined is:
When we were in Europe on vacation, we usually flew on airplanes: however, sometimes we took the train. 
We apply the semi-colon to indicate that they have different ideas, and that they are clauses being joined into one sentence.
        
             
        
        
        
It states a universal truth about life. 
 
        
                    
             
        
        
        
Yes, the correct answer among the following choices given would be option C, " The Swallow dies."