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'.

Input: Consider Input: Problem: a train 284 m in length crosses a telegraph post in 18 seconds . the speed of the train is ?
Options: a ) 77 kmph , b ) 55 kmph , c ) 57 kmph , d ) 58 kmph , e ) 76 kmph

Output: c

Input: Consider 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

Output: d

Input: Consider Input: Problem: if 20 typists can type 48 letters in 20 minutes , then how many letters will 30 typists working at the same rate complete in 1 hour ?
Options: a ) 63 , b ) 72 , c ) 144 , d ) 216 , e ) 400
Output: d