Answer:
A. he plans to fly a plane to follow the pigeon to its owner.
Explanation:
 
        
             
        
        
        
Answer:
1. How long has it been since you came here?
2. How long did your mother watch that play?
3. How long has it been since you met each other?
4. How long has it been since John bought the car?
5.  
Explanation:
 
        
             
        
        
        
I feel 'while' would be the connecting word here. Without it the sentence flops and it helps add onto it with the extra sentence part.
I sharpened your pencil. You were away.
'While' should be the conjunction.