Task: Question Answering
Input (English): Problem: a vessel of capacity 90 litres is fully filled with pure milk . nine litres of milk is removed from the vessel and replaced with water . nine litres of the solution thus formed is removed and replaced with water . find the quantity of pure milk in the final milk solution ? 
Options: a ) 73.9 , b ) 72.9 , c ) 73.0 , d ) 73.5 , e ) 92.2
Output (English): b