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 piece of work in 8 days and b alone can do it in 12 days . how much time will both take to finish the work ? 
Options: a ) a ) 4.8 , b ) b ) 6.333 , c ) c ) 7.333 , d ) d ) 8.5 , e ) e ) 9

Ex Output:
a


Ex Input:
Problem: 9 . on level farmland , two runners leave at the same time from the intersection of two country roads . one runner jogs due north at a constant rate of 8 miles per hour while the second runner jogs due east at a constant rate that is 8 miles per hour faster than the first runner ' s rate . how far apart , to the nearest mile , will they be after 1 / 2 hour ? 
Options: a ) 6 , b ) 7 , c ) 8 , d ) 12 , e ) 9

Ex Output:
e


Ex Input:
Problem: a person crosses a 600 m long street in 5 minutes . what is his speed in km per hour ? 
Options: a ) 3.6 , b ) 7.2 , c ) 8.4 , d ) 10 , e ) 8

Ex Output:

b