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 leak in the bottom of a tank can empty the full tank in 6 hours . an inlet pipe fills water at the rate of 4.5 liters per minute . when the tank is full in inlet is opened and due to the leak the tank is empties in 8 hours . the capacity of the tank is ? 
Options: a ) 5729 , b ) 5760 , c ) 2889 , d ) 6480 , e ) 2799
Example Output: d

Example Input: Problem: a 180 meter long train crosses a man standing on the platform in 9 sec . what is the speed of the train ? 
Options: a ) 72 , b ) 108 , c ) 1266 , d ) 188 , e ) 211
Example Output: a

Example Input: Problem: express a speed of 56 kmph in meters per second ? 
Options: a ) 10.56 mps , b ) 17.56 mps , c ) 97.56 mps , d ) 15.56 mps , e ) 18.56 mps
Example Output:
d