Task: Question Answering
Input (English): Problem: a and b are two partially filled buckets of water . if 5 liters are transferred from a to b , then a would contain one - third of the amount of water in b . alternatively , if 4 liters are transferred from b to a , b would contain one - half of the amount of water in a . bucket a contains how many liters of water ? 
Options: a ) 11 , b ) 52 / 5 , c ) 17 , d ) 21 , e ) 23
Output (English): b