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 can do a work in 8 days . b can do the same work in 16 days . if both a & b are working together in how many days they will finish the work ? 
Options: a ) 3 days , b ) 16 / 3 days , c ) 3 / 4 days , d ) 9 / 12 days , e ) 5 / 7 days

Ex Output:
b


Ex Input:
Problem: the population of a bacteria colony doubles every day . if it was started 8 days ago with 3 bacteria and each bacteria lives for 12 days , how large is the colony today ? 
Options: a ) 512 , b ) 768 , c ) 13122 , d ) 2048 , e ) 4096

Ex Output:
c


Ex Input:
Problem: a man sitting in a train which is traveling at 60 kmph observes that a goods train , traveling in opposite direction , takes 9 seconds to pass him . if the goods train is 280 m long , find its speed . ? 
Options: a ) 52 kmph , b ) 58 kmph , c ) 62 kmph , d ) 65 kmph , e ) 75 kmph

Ex Output:

a