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: on my sister ' s birthday , she was 132 cm in height , having grown 10 % since the year before . how tall was she the previous year ?
Options: a ) 130 cm , b ) 126 cm , c ) 120 cm , d ) 116 cm , e ) 112 cm
Example Output: c

Example Input: Problem: a work as fast as b . if b can complete a work in 8 days independently , the number of days in which a and b can together finish the work in ?
Options: a ) 2 days , b ) 2 2 / 3 days , c ) 4 days , d ) 5 days , e ) 6 days
Example Output:
b