The correct answer is option 1: He/She has to be a retired Chief Justice of India. This means that the Chairperson of the National Human Rights Commission must have previously held the position of Chief Justice of India and is now retired. Option 2 states that the Chairperson must be a retired Supreme Court Judge, which is not entirely accurate as there have been instances where retired Chief Justices of High Courts have been appointed as Chairperson. Option 3 indicates that the Chairperson can be either serving or retired Chief Justice of a High Court, which is not entirely correct as they must specifically be a retired Chief Justice of India. Option 4 suggests that the Chairperson should have demonstrated experience as a Human Rights activist, which is not a prerequisite for the position.