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 Q]: Problem: if one length of a square is tripled , and the original parameter is 4 y . what is the new length of one of the sides ? 
Options: ['a ) 12 y / 3', 'b ) 2 y / 2', 'c ) 6 y / 3', 'd ) 12 y / 4', 'e ) 4 y / 3']
[EX A]: d

[EX Q]: Problem: if 42 men do a work in 25 days , in how many days will 50 men do it ? 
Options: a ) 23 , b ) 22 , c ) 19 , d ) 20 , e ) 21
[EX A]: e

[EX Q]: Problem: a person can swim in still water at 12 km / h . if the speed of water 10 km / h , how many hours will the man take to swim back against the current for 12 km ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
[EX A]:
d