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: in a 500 m race , the ratio of the speeds of two contestants a and b is 3 : 4 . a has a start of 155 m . then , a wins by : 
Options: a ) 60 m , b ) 20 m , c ) 40 m , d ) 20 m , e ) 23 m
Example Output: c

Example Input: Problem: how many seconds will a train 120 meters long take to cross a bridge 200 meters long if the speed of the train is 36 kmph ? 
Options: a ) 22 sec , b ) 32 sec , c ) 25 sec , d ) 24 sec , e ) 31 sec
Example Output: b

Example Input: Problem: a , b , c hired a car for rs . 520 and used it for 7,8 and 11 hours respectively . hire charges paid by b were : 
Options: a ) 160 , b ) 180 , c ) 220 , d ) 225 , e ) none
Example Output:
a