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'.

Example Input: 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']
Example Output: d

Example Input: Problem: if 20 men can build a wall 112 metres long in 6 days , what length of a similar wall can be built by 30 men in 3 days ? 
Options: a ) 65 mtr . , b ) 84 mtr , c ) 70 mtr . , d ) 78 mtr . , e ) 17 mtr .
Example Output: b

Example Input: Problem: an engineer undertakes a project to build a road 15 km long in 300 days and employs 55 men for the purpose . after 100 days , he finds only 2.5 km of the road has been completed . find the ( approximate ) number of extra men he must employ to finish the work in time . 
Options: a ) a . 43 , b ) b . 45 , c ) c . 55 , d ) d . 68 , e ) e . 83
Example Output:
e