Which of the following languages has been declared as the official language of the Government of India?

Article 343 to 351 of the Constitution deals with the official language. Hindi written in Devanagari script is to be the official language of the union. However for the period of 15 years from the date of commencement of constitution English would continue to be used for all the official purposes of union. Act provided for continued use of English even after 1965 for all purpose of union. Further, the Parliament enacted official language Act 1963. Constitution has no provision for the national language.