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: two diagonals of a rhombus are 72 cm and 30 cm respectively . what is its perimeter ? 
Options: ['a ) 136 cm', 'b ) 156 cm', 'c ) 144 cm', 'd ) 121 cm', 'e ) 126 cm']
Example Output: b

Example Input: Problem: two trains of equal length , running with the speeds of 60 and 40 kmph , take 55 seconds to cross each other while they are running in the same direction . what time will they take to cross each other if they are running in opposite directions ? 
Options: a ) 10 sec , b ) 16 sec , c ) 13 sec , d ) 67 sec , e ) 11 sec
Example Output: e

Example Input: Problem: if the wheel is 10 cm then the number of revolutions to cover a distance of 1056 cm is ? 
Options: a ) 16.8 , b ) 26 , c ) 14 , d ) 12 , e ) 91
Example Output:
a