Explanation:

Let's break down the problem step by step:

- Initially, the mixture has Milk and Water in the ratio of 4:3. So, let the quantities of Milk and Water be 4Z/7 and 3Z/7 respectively.

- According to the problem, when 13 liters of water is added, the ratio becomes 1:1. Therefore:

4Z/7 = 3Z/7 + 13

- Solving the above equation for Z, we get: Z = 91

- Therefore, the initial amount of Water is 3*91/7 = 39 liters.

- After adding 13 liters of water, the final quantity becomes 39 + 13 = 52 liters.

- Option 2 (52) is the correct option.