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: 28 machines can do a work in 10 days . how many machines are needed to complete the work in 40 days ? 
Options: a ) 10 , b ) 6 , c ) 4 , d ) 7 , e ) 5
Example Output: d

Example Input: Problem: a rhombus has area 432 sq m , one diagonal is 36 cm . find other diagonal ? 
Options: ['a ) 2400 m', 'b ) 2500 m', 'c ) 2600 m', 'd ) 2700 m', 'e ) 2900 m']
Example Output: a

Example Input: Problem: a goods train runs at the speed of 72 kmph and crosses a 280 m long platform in 26 seconds . what is the length of the goods train ? 
Options: a ) 230 m , b ) 270 m , c ) 240 m , d ) 832 m , e ) 270 m
Example Output:
c