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 train 250 m long running at 72 kmph crosses a platform in 15 sec . what is the length of the platform ?
Options: a ) 50 m , b ) 200 m , c ) 250 m , d ) 270 m , e ) 300 m

Ex Output:
a

Ex Input:
Problem: 3 different containers contain 496 litres , 403 litres and 713 litres of mixtures of milk and water respectively . what biggest measure can measure all the different quantities exactly ?
Options: a ) 30 litres , b ) 31 litres , c ) 32 litres , d ) 33 litres , e ) 34 litres

Ex Output:
b

Ex Input:
Problem: a take twice as much time as b or thrice as much time to finish a piece of work . working together , they can finish the work in 7 days . b can do the work alone in ?
Options: a ) 19 , b ) 12 , c ) 11 , d ) 42 , e ) 114

Ex Output:
d