Solution:(d) As was customary, the palace staff brought the young prince to the podium in a diamond studded carriage for the coronation ceremony. (Correct)(a) As was customary, the young prince brings himself to the podium in a diamond studded carriage for the coronation ceremony. (Incorrect Sentence Structure)
(b) As was customary, the young prince is bought to the podium in a diamond studded carriage for the coronation ceremony. (Incorrect Sentence Structure)
(c) As was customary, the young prince brought in a diamond studded carriage to the podium for the coronation ceremony. (Incorrect Sentence Structure)