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 the wheel is 21 cm then the number of revolutions to cover a distance of 1056 cm is ? 
Options: a ) 8 , b ) 27 , c ) 10 , d ) 7 , e ) 19
Example Output: a

Example Input: Problem: five bells commence tolling together and toll at intervals of 2 , 4 , 6 , 8 10 seconds respectively . in 20 minutes , how many times do they toll together ? 
Options: a ) 11 , b ) 10 , c ) 15 , d ) 16 , e ) 17
Example Output: a

Example Input: Problem: a train overtakes two persons who are walking in the same direction to that of the train at 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively . what is the length of the train ? 
Options: a ) 62 m , b ) 54 m , c ) 50 m , d ) 55 m , e ) 56 m
Example Output:
c