In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Input: Consider Input: Problem: the difference between a 7 digit number and the number formed by reversing its digit is not a multiple of 
Options: a ) 121 , b ) 11 , c ) 9 , d ) 10 , e ) 3

Output: a


Input: Consider Input: Problem: if a person walks at 14 km / hr instead of 10 km / hr , he would have walked 20 km more . the actual distance traveled by him is : 
Options: a ) 50 km , b ) 56 km , c ) 60 km , d ) 70 km , e ) 80 km

Output: a


Input: Consider Input: Problem: on a certain date , pat invested $ 10,000 at x percent annual interest , compounded annually . if the total value of the investment plus interest at the end of 12 years will be $ 40,000 , in how many years , the total value of the investment plus interest will increase to $ 120,000 ? 
Options: a ) 15 , b ) 21 , c ) 18 , d ) 20 , e ) 24


Output: b