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: a man can row upstream at 20 kmph and downstream at 60 kmph , and then find the speed of the man in still water ?
Options: a ) 32 kmph , b ) 34 kmph , c ) 30 kmph , d ) 45 kmph , e ) 40 kmph
Example Output: e

Example Input: Problem: a prison of 10,000 inmates has enough food to feed them all for 50 days . after 10 days some of the inmates leave and the food is now enough for the same period of 50 days as before . how many of them left ?
Options: a ) 3,000 , b ) 2,200 , c ) 2,000 , d ) 1,000 , e ) 200
Example Output: c

Example Input: Problem: on my sister ' s birthday , she was 154 cm in height , having grown 10 % since the year before . how tall was she the previous year ?
Options: a ) 150 cm , b ) 140 cm , c ) 142 cm , d ) 148 cm , e ) 146 cm
Example Output:
b