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 250 meter long train crosses a man standing on the platform in 12 sec . what is the speed of the train ? 
Options: a ) 228 , b ) 108 , c ) 1266 , d ) 75 , e ) 211
Example Output: d

Example Input: Problem: 9 spheres of the same size are made from melting a solid cylinder of 16 cm diameter and 12 cm height . what is the diameter of each sphere ? 
Options: ['a ) 4 cm', 'b ) 6 cm', 'c ) 8 cm', 'd ) 10 cm', 'e ) 12 cm']
Example Output: c

Example Input: Problem: two trains 250 m and 500 m long run at the speed of 60 km / hr and 40 km / hr respectively in opposite directions on parallel tracks . the time which they take to cross each other is ? 
Options: a ) 10.6 , b ) 10.9 , c ) 10.4 , d ) 27 , e ) 10.1
Example Output:
d