The correct option is B 24 litres
Let the quantity of the wine in the cask originally be x litres.
After first operation, wine left in the cask =(x−8) litres.
So, the ratio of the quantity of wine now left in cask to that of filled cask =x−8x
This operation is performed three more times.
Then, Wine : Water =16:65
or, Wine : Total =16:81
⇒(x−8x)4=1681
⇒x−8x=23
⇒3x−24=2x
⇒x=24 litres