Indian Polity · Polity

In the context of discussions on secularism and constitutional values in India, consider the following statements: I. The word 'Secular' was inserted into the Preamble by a constitutional amendment and was not part of the original text at the commencement of the Constitution. II. Secularism has been recognised by the Supreme Court as a part of the Basic Structure of the Constitution. III. The duty to promote harmony and the spirit of common brotherhood, transcending religious diversities, forms part of the Fundamental Duties of citizens. Which of the statements given above is/are correct?