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: 42 persons can repair a road in 12 days , working 5 hours a day . in how many days will 30 persons , working 6 hours a day , complete the work ? 
Options: a ) 10 , b ) 16 , c ) 13 , d ) 14 , e ) 19
Example Output: d

Example Input: Problem: jake can dig a well in 16 days . paul can dig the same well in 24 days . jake , paul and hari together dig the well in 8 days . hari alone can dig the well in 
Options: a ) 96 days , b ) 48 days , c ) 32 days , d ) 24 days , e ) 28 days
Example Output: b

Example Input: Problem: a can do a job in 15 days and b can do it in 30 days . a and b working together will finish twice the amount of work in - - - - - - - days ? 
Options: a ) 14 days , b ) 16 days , c ) 20 days , d ) 11 days , e ) 19 days
Example Output:
c