If it appears to a district director that an alien residing in his district, who was lawfully admitted for permanent residence, has an occupational status described in section 247 of the Act, he shall cause a notice on Form I-509 to be served on such alien by personal service informing him that it is proposed to adjust his status, unless the alien requests that he be permitted to retain his status as a resident alien and executes and files with such district director a Form I-508 (Waiver of Rights, Privileges, Exemptions and Immunities) and, if a French national receiving salary from the French Republic, Form I-508F (election as to tax exemption under the Convention between the United States and the French Republic), within 10 days after service of the notice, or the alien, within such 10-day period, files with the district director a written answer under oath setting forth reasons why his status should not be adjusted. The notice shall also advise the person that he may, within such period and upon his request have an opportunity to appear in person, in support or in lieu of his written answer, before an immigration officer designated for that purpose. The person shall further be advised that he may have the assistance of counsel without expense to the Government of the United States in the preparation of his answer or in connection with such personal appearance, and may examine the evidence upon which it is proposed to base such adjustment.