What quantity of water should taken out to concentrate 12 liters of 40% acidic liquid to 60% acidic liquid?  Choose the correct choice from the following choices
A) 4 liters
B) 10 liters
C) 15 liters
D) 8 liters
E) 6 liters

Rationale: "required answer is = 12 ( 60 - 40 ) / 60 = 4 liters answer is a"
Answer: A