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: to fill a tank , 25 buckets of water is required . how many buckets of water will be required to fill the same tank if the capacity of the bucket is reduced to 3 / 10 of its present ?
Options: a ) 61.5 , b ) 60.5 , c ) 63.5 , d ) 83.333 , e ) 64.5
Example Output: d

Example Input: Problem: what is the maximum number of pieces of birthday cake of size 5 " by 5 " that can be cut from a cake 15 " by 15 " ?
Options: a ) 5 , b ) 10 , c ) 16 , d ) 20 , e ) 9
Example Output: e

Example Input: Problem: two pipes a and b can fill a tank in 20 and 30 minutes respectively . if both the pipes are used together , then how long it will take to fill the tank ?
Options: a ) 10 mins , b ) 12 mins , c ) 15 mins , d ) 20 mins , e ) 30 mins
Example Output:
b