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 trains a and b are 125 m and 150 m long and are moving at one another at 54 km / hr and 36 km / hr respectively . arun is sitting on coach b 1 of train a . calculate the time taken by arun to completely cross train b . 
Options: a ) 10 s , b ) 11 s , c ) 4 s , d ) 8 s , e ) 12 s
Example Output: b

Example Input: Problem: what is the minimum number of square tiles required to tile a floor of length 5 metres 78 cm and width 3 metres 74 cm ? 
Options: a ) 187 , b ) 180 , c ) 190 , d ) 195 , e ) 197
Example Output: a

Example Input: Problem: a cistern is filled by a tap in 8 1 / 2 hours . due to leak in the bottom of the cistern , it takes half an hour longer to fill the cistern . if the cistern is full how many hours will it take the leak to empty it ? 
Options: a ) 133 , b ) 143 , c ) 153 , d ) 163 , e ) 173
Example Output:
c