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'.

Example Input: Problem: two men a and b start from place x walking at 4 ½ kmph and 5 ¾ kmph respectively . how many km apart they are at the end of 4 ½ hours if they are walking in the same direction ? 
Options: a ) 7 km , b ) 6 km , c ) 5 5 / 8 km , d ) 9 km , e ) 5 km
Example Output: c

Example Input: Problem: a man can row downstream at 16 kmph and upstream at 10 kmph . find the speed of the man in still water and the speed of stream respectively ? 
Options: a ) 3 , b ) 5 , c ) 6 , d ) 4 , e ) 9
Example Output: a

Example Input: Problem: two trains a and b are 225 m and 150 m long and are moving at one another at 54 km / hr and 36 km / hr respectively . arun is sitting on coach b 1 of train a . calculate the time taken by arun to completely cross train b . 
Options: a ) 10 s , b ) 15 s , c ) 4 s , d ) 8 s , e ) 12 s
Example Output:
b