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: it is currently 7 : 05 pm . what time was it in the morning exactly 51,132 minutes ago ?
Options: a ) 6 : 53 , b ) 6 : 55 , c ) 6 : 59 , d ) 7 : 03 , e ) 7 : 09
Example Output: a

Example Input: Problem: a water tank is four - fifths full . pipe a can fill a tank in 10 minutes and pipe b can empty it in 6 minutes . if both the pipes are open , how many minutes will it take to empty or fill the tank completely ?
Options: a ) 6 , b ) 9 , c ) 10 , d ) 12 , e ) 15
Example Output: d

Example Input: Problem: the first , second and third terms of the proportion are 56 , 16 , 49 . find the fourth term .
Options: a ) 10 , b ) 14 , c ) 40 , d ) 50 , e ) 60
Example Output:
b