Correct Answer - Option 4 : 175 liters

**Given:**

The ratio of milk and water is 7 ∶ 4

After adding 5 liters of water, the ratio of milk and water is 5 ∶ 3

**Calculation:**

Let the quantity of milk and water be 7x and 4x

According to the question, we have,

⇒ 7x/(4x + 5) = 5/3

⇒ 21x = 20x + 25

⇒ 21x - 20x = 25

⇒ x = 25

Now, the initial quantity of milk is

⇒ 7x = 7 × 25

⇒ 175 liters

**∴ The quantity of milk in the initial mixture is 175 liters.**