The ratio of volumes of 3 containers is 3 ∶ 4 ∶ 5. All the three containers are full of a mixture of milk and water. The ratio of milk and water is 4 ∶ 1, 3 ∶ 1, and 3 ∶ 2 in the three containers respectively. If the liquid of all three containers is poured in the 4th container, then find the ratio of milk and water.

• A. 3 ∶ 7
• B. 7 ∶ 3
• C. 6 ∶ 5
• D. 7 ∶ 4