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 boat covers a certain distance downstream in 1 hour , while it comes back in 1 hours . if the speed of the stream be 3 kmph , what is the speed of the boat in still water ?
Options: a ) 12 kmph , b ) 13 kmph , c ) 14 kmph , d ) 15 kmph , e ) none

Ex Output:
d

Ex Input:
Problem: a can do a piece of work in 4 hours ; b and c together can do it in 2 hours , while a and c together can do it in 2 hours . how long will b alone take to do it ?
Options: a ) 12 , b ) 9 , c ) 8 , d ) 6 , e ) 4

Ex Output:
e

Ex Input:
Problem: 1480 men have provisions for 14 days . if 460 more men join them , for how many days will the provisions last now ?
Options: a ) 9.9 , b ) 8.0 , c ) 12.5 , d ) 12.2 , e ) 12.1

Ex Output:
a