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 , b and c can complete a piece of work in 24 , 6 and 12 days respectively . working together , they will complete the same work in : 
Options: a ) 33 / 7 , b ) 43 / 7 , c ) 24 / 7 , d ) 19 / 7 , e ) none

Ex Output:
c


Ex Input:
Problem: walking with 4 / 5 of my usual speed , i arrive at the bus stop 7 minutes later than normal . how many minutes does it take to walk to the bus stop at my usual speed ? 
Options: a ) 12 , b ) 16 , c ) 20 , d ) 24 , e ) 28

Ex Output:
e


Ex Input:
Problem: a and b can do a piece of work in 50 days and 50 days respectively . they work together for 10 days and b leaves . in how many days the whole work is completed ? 
Options: a ) 30 days , b ) 35 days , c ) 40 days , d ) 44 days , e ) 45 days

Ex Output:

a