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: mariah has decided to hire three workers . to determine whom she will hire , she has selected a group of 12 candidates . she plans to have one working interview with 3 of the 12 candidates every day to see how well they work together . how many days will it take her to have working interviews with all the different combinations of job candidates ? 
Options: a ) 720 , b ) 120 , c ) 300 , d ) 30 , e ) 333

Ex Output:
c


Ex Input:
Problem: the sum of two consecutive integers is 61 . find the numbers . 
Options: a ) 17 , 18 , b ) 30,31 , c ) 5 , 6 , d ) 1 , 2 , e ) 8 , 9

Ex Output:
b


Ex Input:
Problem: a cistern is filled by pipe a in 20 hours and the full cistern can be leaked out by an exhaust pipe b in 25 hours . if both the pipes are opened , in what time the cistern is full ? 
Options: a ) 50 hrs , b ) 60 hrs , c ) 70 hrs , d ) 80 hrs , e ) 100 hrs

Ex Output:

e