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: ajay can walk 6 km in 1 hour . in how many hours he can walk 70 km ? 
Options: a ) 5 hrs , b ) 11.6 hrs , c ) 15.6 hrs , d ) 20.1 hrs , e ) 30 hrs
Example Output: b

Example Input: Problem: a contractor undertakes to built a walls in 50 days . he employs 20 peoples for the same . however after 25 days he finds that only 40 % of the work is complete . how many more man need to be employed to complete the work in time ? 
Options: a ) 25 , b ) 30 , c ) 35 , d ) 30 , e ) none of these
Example Output: d

Example Input: Problem: a is twice as fast as b . if b alone can do a piece of work in 30 days , in what time can a and b together complete the work ? 
Options: a ) 13 , b ) 10 , c ) 16 , d ) 50 , e ) 23
Example Output:
b