Explanation:

Correct Answer is (d).The statement conveys that even though Untouchability was abolished under Article 17 of the Constitution, the caste system, which is the root cause of it, was not abolished, and still persists.
The original fragment is incorrect as the two fragments state a contradictory point and using ‘and’ as a connector is incorrect. Use of ‘and’ is used to signify when both fragments complement/ strengthen each other.
Option A is incorrect as it seems to imply that because untouchability was abolished, the caste system was not. This is meaningless.
Option B is incorrect as the sentence structure renders the statement meaningless. Notwithstanding means despite/even though and is correct in terms of meaning but incorrect in terms of the way the sentence has been structured.
Option C is incorrect as ‘likewise’ is used to indicate similar things/instances while here one action has been carried out but its root cause still persists.
Option D is correct and uses the correct connector to indicate contradiction.
Hence, option D is correct.