Given below are two quantities named A and B. Based on the given information, you have to determine the relationship between the two quantities. You should use the given data and your knowledge of Mathematics to choose among the possible answers.

There are two containers∶ the first contains 500 ml. of milk, while the second contains 500 ml. of water. 3 glasses of milk from the first container is taken out and mixed well in the second container. Then, 3 glasses from second container is taken out and mixed in the first container.

Quantity A∶ Quantity of water in first container.

Quantity B∶ Quantity of milk in second container.