Task: Question Generation
Input (English): #1 return musicians 
#2 return positions of #1 
#3 return #2 that are in  the  back 
#4 return number of  #3 for each #1 
#5 return #1 where #4 is the  highest 
#6 return last names of #5
Output (English): What is the last name of the musicians who has played back position the most?