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 can do a work in 4 days . b can do the same work in 6 days . both a & b together will finish the work and they got $ 1000 from that work . find their shares ? 
Options: a ) 600,400 , b ) 500,500 , c ) 300,700 , d ) 800,200 , e ) 550,450
Example Output: a

Example Input: Problem: at a speed of 50 miles per hour , a certain car uses 1 gallon of gasoline every 30 miles . if the car starts with a full 10 gallon tank of gasoline and travels for 5 hours at 50 miles per hour , the amount of gasoline used would be what fraction of a full tank ? 
Options: a ) 3 / 25 , b ) 5 / 6 , c ) 7 / 12 , d ) 2 / 3 , e ) 25 / 36
Example Output: b

Example Input: Problem: three pipes a , b and c can fill a tank from empty to full in 30 minutes , 20 minutes and 10 minutes respectively . when the tank is empty , all the three pipes are opened . a , b and c discharge chemical solutions p , q and r respectively . what is the proportion of solution r in the liquid in the tank after 3 minutes ? 
Options: a ) 6 / 15 , b ) 6 / 11 , c ) 6 / 14 , d ) 6 / 12 , e ) 6 / 13
Example Output:
b