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 what time will a train 20 m long cross an electric pole , it its speed be 144 km / hr ? 
Options: a ) 2.5 sec , b ) 2.8 sec , c ) 0.5 sec , d ) 2.3 sec , e ) 1.5 sec
Example Output: c

Example Input: Problem: the speed of a train is 120 kmph . what is the distance covered by it in 40 minutes ? 
Options: a ) 50 kmph , b ) 60 kmph , c ) 70 kmph , d ) 80 kmph , e ) 85 kmph
Example Output: d

Example Input: Problem: 1000 men have provisions for 18 days . if 400 more men join them , for how many days will the provisions last now ? 
Options: a ) 12.9 , b ) 12.8 , c ) 12.6 , d ) 12.2 , e ) 12.1
Example Output:
b