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 and b can do a piece of work in 3 days , b and c in 4 days , c and a in 6 days . how long will c take to do it ? 
Options: a ) 33 , b ) 77 , c ) 24 , d ) 55 , e ) 71

Ex Output:
c


Ex Input:
Problem: a flagpole 18 meters high casts a shadow of length 45 meters . if a building under similar conditions casts a shadow of length 55 meters , what is the height of the building ( in meters ) ? 
Options: a ) 20 , b ) 22 , c ) 24 , d ) 26 , e ) 28

Ex Output:
b


Ex Input:
Problem: find the cost of fencing around a circular field of diameter 30 m at the rate of rs . 2 a meter ? 
Options: a ) 100.5 , b ) 188.5 , c ) 190.5 , d ) 168.5 , e ) 175.5

Ex Output:

b