20 litres of a mixture contains milk and water in the ratio 3 : 1. Then the amount of milk to be added to the mixture so as to have milk and water in ratio 4 : 1 is -

• ক 20 litres
• খ 15 litres
• গ 5 litres ✅ সঠিক উত্তর
• ঘ 25 litres