Explanation:

- Option 1: Untouchability

- Correct Answer: Article 17 of the Constitution of India abolishes "untouchability" and forbids its practice in any form. It ensures dignity and equality.

- Option 2: Slavery

- Article 23 of the Indian Constitution relates to the prohibition of traffic in human beings and forced labor, indirectly dealing with slavery.

- Option 3: Titles

- Article 18 deals with the abolition of titles, prohibiting the state from conferring any titles except military or academic distinctions.

- Option 4: Sati

- Sati was abolished through legislative measures, not an article. The Sati Prevention Act of 1987 made its practice punishable by law.