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: a man can row a boat at 10 kmph in still water and the speed of the stream is 8 kmph . what is then time taken to row a distance of 90 km down the stream ? 
Options: a ) 8 hrs , b ) 5 hrs , c ) 15 hrs , d ) 15 hrs , e ) 20 hrs

Ex Output:
b


Ex Input:
Problem: a cistern is normally filled in 10 hrs , but takes 2 hrs longer to fill because of a leak on its bottom , if cistern is full , how much time citern would empty ? 
Options: a ) 10 hours , b ) 20 hours , c ) 60 hours , d ) 40 hours , e ) 50 hours

Ex Output:
c


Ex Input:
Problem: a and b can do a piece of work in 10 days . with the help of c they finish the work in 5 days . c alone can do that piece of work in ? 
Options: a ) 33 , b ) 878 , c ) 30 , d ) 10 , e ) 11

Ex Output:

d