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: two trains of equal lengths take 10 sec and 8 sec respectively to cross a telegraph post . if the length of each train be 120 m , in what time will they cross other travelling in opposite direction ? 
Options: a ) 22 , b ) 12 , c ) 9 , d ) 99 , e ) 21

Ex Output:
c


Ex Input:
Problem: the radius of the wheel of a bus is 70 cms and the speed of the bus is 66 km / h , then the r . p . m . ( revolutions per minutes ) of the wheel is 
Options: a ) 200 , b ) 250 , c ) 300 , d ) 330 , e ) none of these

Ex Output:
b


Ex Input:
Problem: a , b and c can do a piece of work in 4 days , 8 days and 20 days respectively . how long will they taken , if all the three work together ? 
Options: a ) 2 , b ) 4 , c ) 5 , d ) 67 , e ) 2 6 / 17

Ex Output:

e