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 20 men can build a wall 112 metres long in 6 days , what length of a similar wall can be built by 30 men in 3 days ? 
Options: a ) 65 mtr . , b ) 84 mtr , c ) 70 mtr . , d ) 78 mtr . , e ) 17 mtr .
Example Output: b

Example Input: Problem: how many seconds will a train 120 meters long take to cross a bridge 200 meters long if the speed of the train is 36 kmph ? 
Options: a ) 22 sec , b ) 32 sec , c ) 25 sec , d ) 24 sec , e ) 31 sec
Example Output: b

Example Input: Problem: a tank with a volume of 45 cubic feet has one inlet pipe and 2 outlet pipes . the inlet pipe fills water into the tank at the rate of 5 cubic inches / min and the 2 outlet pipes empty it out at the rates of 14 cubic inches / min and 6 cubic inches / min respectively . if all 3 pipes are opened when the tank is full , how many minutes does it take to empty the tank ? ( 1 foot = 12 inches ) 
Options: a ) 5184 , b ) 5276 , c ) 5368 , d ) 5460 , e ) 5552
Example Output:
a