Explanation:

- Option 1: Untouchability

- Article 17 of the Constitution of India abolishes untouchability.

- It prohibits discrimination based on caste and declares untouchability a punishable offense.

- Correct Answer

- Option 2: Slavery

- Slavery was abolished globally through various conventions, and India adheres to these.

- It is not specifically addressed in Article 17.

- Option 3: Titles

- The abolition of titles is covered under Article 18.

- It prohibits the state from conferring any titles except military or academic distinctions.

- Option 4: Sati

- Sati, the practice of a widow self-immolating on her husband's pyre, was abolished through specific legislation like the Sati Prevention Act.

- It is not addressed in Article 17.