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: a tank can be filled by two pipes a and b in 60 minutes and 40 minutes respectively . how many minutes will it take to fill the tank from empty state if b is used for the first half time and then a and b fill it together for the other half .
Options: a ) 15 mins , b ) 20 mins , c ) 25 mins , d ) 30 mins , e ) 35 mins
Example Output: d

Example Input: Problem: a and b can together finish a work in 40 days . they worked together for 10 days and then b left . after another 18 days , a finished the remaining work . in how many days a alone can finish the job ?
Options: a ) 10 , b ) 24 , c ) 60 , d ) 30 , e ) 20
Example Output: b

Example Input: Problem: a cistern 10 m long and 8 m wide contains water up to a depth of 1 m 50 cm . the total area of the wet surface is :
Options: a ) 120 m 2 , b ) 136 m 2 , c ) 128 m 2 , d ) 130 m 2 , e ) 134 m 2
Example Output:
e