A drum contains 40 litres of milk. One-fourth of the milk is taken out and replaced with water. Then, half of the mixture is taken out and replaced with water. What is the respective quantity of milk and water left in the drum?

A

15 litres and 25 litres

B

10 litres and 30 litres

C

20 litres and 20 litres

D

25 litres and 15 litres