The correct answer is option 4, which is "abolition of untouchability." Article 17 of the Indian Constitution specifically addresses the issue of untouchability, which is the practice of discriminating against and segregating individuals based on their caste or social status. This article prohibits untouchability in any form and declares it as a punishable offense. The inclusion of Article 17 in the Indian Constitution reflects the commitment of the Indian government to eradicate this social evil and promote equality among all citizens. It is important to note that while equality before the law (option 1), equality of opportunity in matters of public employment (option 2), and abolition of titles (option 3) are also important principles enshrined in the Indian Constitution, they are addressed in other articles and not specifically mentioned in Article 17.