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: a courtyard is 25 meter long and 16 meter board is to be paved with bricks of dimensions 20 cm by 10 cm . the total number of bricks required is 
Options: a ) 16000 , b ) 18000 , c ) 20000 , d ) 22000 , e ) 24000
Example Output: c

Example Input: Problem: a contractor undertakes to built a walls in 50 days . he employs 20 peoples for the same . however after 25 days he finds that only 40 % of the work is complete . how many more man need to be employed to complete the work in time ? 
Options: a ) 25 , b ) 30 , c ) 35 , d ) 30 , e ) none of these
Example Output: d

Example Input: Problem: an engineer undertakes a project to build a road 10 km long in 300 days and employs 30 men for the purpose . after 100 days , he finds only 2 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 ) 20 , b ) 25 , c ) 30 , d ) 35 , e ) 40
Example Output:
c