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

Ex Input:
Problem: 13 buckets of water fill a tank when the capacity of each bucket is 51 litres . how many buckets will be needed to fill the same tank , if the capacity of each bucket is 17 litres ? 
Options: a ) 39 , b ) 28 , c ) 23 , d ) 12 , e ) 24

Ex Output:
a


Ex Input:
Problem: a train passes a station platform in 20 sec and a man standing on the platform in 12 sec . if the speed of the train is 72 km / hr . what is the length of the platform ? 
Options: a ) 227 , b ) 140 , c ) 160 , d ) 120 , e ) 171

Ex Output:
c


Ex Input:
Problem: calculate the time it will take for a train that is 200 meter long to pass a bridge of 180 meter length , if the speed of the train is 65 km / hour ? 
Options: a ) 20 seconds , b ) 4 seconds , c ) 31.04 seconds , d ) 11.04 seconds , e ) 21.04 seconds

Ex Output:

e