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: 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 certain bacteria colony doubles in size every day for 20 days , at which point it reaches the limit of its habitat and can no longer grow . if two bacteria colonies start growing simultaneously , how many days will it take them to reach the habitat ’ s limit ? 
Options: a ) 6.33 , b ) 7.5 , c ) 10 , d ) 15 , e ) 19
Example Output: e

Example Input: Problem: how many seconds will it take for a car that is traveling at a constant rate of 77 miles per hour to travel a distance of 21 yards ? ( 1 mile = 1,160 yards ) 
Options: a ) . 1 , b ) 0.3 , c ) 0.6 , d ) 2 , e ) 1.6
Example Output:
c