python

Suppose you have a list of tuples containing first and last names, for example: names =[( 'john' , 'dough' ),( 'jane', 'dough' ),( jjohn', 'doe' ),( 'jan You want to write a key function named to pass to the built-in function so that it returns a list sorted by last name and then first name. For example: print(sorted(names, key=last_first)) '' Output ''' [('jane', 'doe'), ('john', 'doe'), ('jane', 'dough'), ('john', Which of the following function definitions is correct for last_first? def last_first(pair): return (pair[0],pair[1]) def last_first(pair): return pair[0] def last_first(pair): return (pair[1],pair[0]) def last_first(pair): return pair[1]