Task: Question Answering
Input (English): Problem: if each digit in the set a = { 1 , 2 , 3 , 4 , 5 , 6 , 7 } is used exactly once , in how many ways can the digits be arranged ? 
Options: a ) 4830 , b ) 5040 , c ) 5250 , d ) 5460 , e ) 5680
Output (English): b