Explanation:

- Pair I: Separation of Judiciary from the Executive in the public services of the State — The Directive Principles of the State Policy

- Correct. This is stated under the Directive Principles, specifically Article 50.

- Pair II: Valuing and preserving the rich heritage of our composite culture — The Fundamental Duties

- Correct. This is included in the Fundamental Duties, specifically Article 51A(f).

- Pair III: Prohibition of employment of children below the age of 14 years in factories — The Fundamental Rights

- Correct. This is covered under the Fundamental Rights, specifically Article 24.

- Correct Answer: Option 3, All the three