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: it takes joey the postman 1 hours to run a 7 mile long route every day . he delivers packages and then returns to the post office along the same path . if the average speed of the round trip is 8 mile / hour , what is the speed with which joey returns ? 
Options: a ) 11 , b ) 12 , c ) 13 , d ) 8 , e ) 15
Example Output: d

Example Input: Problem: a is twice as good a workman as b and together they complete a work in 12 days . in how many days a alone can do the work ? 
Options: a ) 32 , b ) 33 , c ) 34 , d ) 35 , e ) 36
Example Output: e

Example Input: Problem: a man swims downstream 40 km and upstream 16 km taking 4 hours each time , what is the speed of the man in still water ? 
Options: a ) 7 , b ) 7.5 , c ) 6.8 , d ) 7.8 , e ) 8.0
Example Output:
b