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'.

Ex Input:
Problem: average age of students of an adult school is 42 years . 120 new students whose average age is 32 years joined the school . as a result the average age is decreased by 4 years . find the number of students of the school after joining of the new students . 
Options: a ) 1200 , b ) 120 , c ) 360 , d ) 200 , e ) none of these

Ex Output:
d


Ex Input:
Problem: robert ate 13 chocolates , nickel ate 4 chocolates . how many more chocolates did robert ate than nickel ? 
Options: a ) a ) 4 , b ) b ) 7 , c ) c ) 9 , d ) d ) 5 , e ) e ) 2

Ex Output:
c


Ex Input:
Problem: if henry were to add 9 gallons of water to a tank that is already 3 / 4 full of water , the tank would be 7 / 8 full . how many gallons of water would the tank hold if it were full ? 
Options: a ) 25 , b ) 40 , c ) 64 , d ) 72 , e ) 96

Ex Output:

d