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 120 m long running at 60 kmph crosses a platform in 20 sec . what is the length of the platform ? 
Options: a ) 213 , b ) 298 , c ) 350 , d ) 726 , e ) 267
Example Output: a

Example Input: Problem: a tiger is chasing its prey at a constant speed . it entire body passes a blade of grass in 1 second . it then runs above a fallen tree trunk that is 20 meters long in 5 seconds . what is the length of the tiger ? 
Options: a ) 6 m , b ) 5 m , c ) 4 m , d ) 3 m , e ) none of the above
Example Output: b

Example Input: Problem: two trains , one from howrah to patna and the other from patna to howrah , start simultaneously . after they meet , the trains reach their destinations after 16 hours and 9 hours respectively . the ratio of their speeds is ? 
Options: a ) 4 : 5 , b ) 4 : 3 , c ) 4 : 4 , d ) 4 : 9 , e ) 3 : 4
Example Output:
e