Concept:
The Indian Constitution guarantees equality and abolishes discriminatory social practices.
Step 1:
Untouchability was a social practice in which certain groups were discriminated against and treated as socially inferior.
Step 2:
Article 17 of the Indian Constitution abolishes untouchability and prohibits its practice in any form.
Step 3:
• Article 15 prohibits discrimination on grounds of religion, race, caste, sex, or place of birth.
• Article 12 defines the term “State”.
• Article 13 deals with laws inconsistent with Fundamental Rights.
Step 4:
Therefore, the correct answer is Article 17.
\[
\boxed{\text{(2) Article-17}}
\]