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 24 days and b can do it in 8 days . in how many days a and b can do the work ? 
Options: a ) 20 days , b ) 10 days , c ) 6 days , d ) 8 days , e ) 7 days

Ex Output:
c


Ex Input:
Problem: joe needs to paint all the airplane hangars at the airport , so he buys 360 gallons of paint to do the job . during the first week , he uses 1 / 4 of all the paint . during the second week , he uses 1 / 4 of the remaining paint . how many gallons of paint has joe used ? 
Options: a ) 18 , b ) 157 , c ) 175 , d ) 216 , e ) 250

Ex Output:
b


Ex Input:
Problem: a train covers a distance of 12 km in 10 min . if it takes 7 sec to pass a telegraph post , then the length of the train is ? 
Options: a ) 177 m , b ) 189 m , c ) 140 m , d ) 178 m , e ) 188 m

Ex Output:

c