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'.

Ex Input:
Problem: a can do a work in 8 days . b can do the same work in 16 days . if both a & b are working together in how many days they will finish the work ? 
Options: a ) 3 days , b ) 16 / 3 days , c ) 3 / 4 days , d ) 9 / 12 days , e ) 5 / 7 days

Ex Output:
b


Ex Input:
Problem: a hiker walking at a constant rate of 4 kilometers per hour is passed by a cyclist travelling in the same direction along the same path at a constant rate of 30 kilometers per hour . the cyclist stops and waits for the hiker 5 minutes after passing her while the hiker continues to walk at her constant rate . how many minutes must the cyclist wait until the hiker catches up ? 
Options: a ) 7.5 , b ) 15 , c ) 17.5 , d ) 25 , e ) 32.5

Ex Output:
e


Ex Input:
Problem: if a is thrice as fast as b and together can do a work in 21 days . in how many days a alone can do the work ? 
Options: a ) 36 , b ) 42 , c ) 28 , d ) 54 , e ) 45

Ex Output:

c