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 constructor estimates that 3 people can paint mr khans house in 4 days . if he uses 4 people instead of 3 , how long will they take to complete the job ? 
Options: a ) 2 , b ) 8 , c ) 1 , d ) 3 , e ) 4

Ex Output:
d


Ex Input:
Problem: from an island , it is possible to reach the mainland by either ferry p or ferry q . ferry p travels for 3 hours at 6 kilometers per hour , while ferry q takes a route that is three times longer . if ferry p is slower than ferry q by 3 kilometers per hour , how many hours longer is the journey of ferry q compared with the journey of ferry p ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5

Ex Output:
c


Ex Input:
Problem: marla starts running around a circular track at the same time nick starts walking around the same circular track . marla completes 28 laps around the track per hour and nick completes 13 laps around the track per hour . how many minutes after marla and nick begin moving will marla have completed 4 more laps around the track than nick ? 
Options: a ) 5 , b ) 8 , c ) 12 , d ) 16 , e ) 20

Ex Output:

d