The correct answer is “None of the Courts”.
Article 124(7): It prohibits a retired judge of the Supreme Court from practising before any court or authority in India.
The Chief Justice of India, with the President's consent, may request a retired Judge of the Supreme Court, Federal Court, or High Court qualified for Supreme Court appointment to sit and act as a Supreme Court Judge.
Article 220: It bars High Court judges from pleading before "any authority in India except the Supreme Court and the other High Courts."