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 train 605 m long is running with a speed of 60 km / hr . in what time will it pass a man who is running at 6 km / hr in the direction opposite to that in which the train is going ? 
Options: a ) 81 , b ) 16 , c ) 33 , d ) 54 , e ) 12
Example Output: c

Example Input: Problem: a train takes 10 sec to pass a signal post and covers a distance of 10 km in 15 min . find the length of train ? 
Options: a ) 100.1 m , b ) 223.1 m , c ) 111.1 m , d ) 120.3 m , e ) 133.4 m
Example Output: c

Example Input: Problem: an woman swims downstream 45 km and upstream 25 km taking 5 hours each time ; what is the speed of the current ? 
Options: a ) 2 , b ) 1 , c ) 3 , d ) 4 , e ) 2.1
Example Output:
a