Explanation:

- Option 1: 15th Aug, 1947 marks India’s Independence Day, when India gained freedom from British rule.

- Option 2: 26th Nov, 1949 is when the Constitution of India was adopted by the Constituent Assembly.

- Option 3: 26th Jan, 1950 is the day the Indian Constitution came into force and India became a republic. This date is chosen to commemorate the declaration of Purna Swaraj in 1930.

- Option 4: 30th Jan, 1950 is not associated with any major constitutional event in India.

Option 3 - 26th Jan, 1950 is the correct answer.