6. An officer to whom this part of these Rules applies and who, on his retirement from the office of Governor, would become eligible for the grant of a pension under the provisions of section 2 of the Pensions (Governors of Dominions, etc.) Act, 1929, shall elect within the three months next before the date of his retirement from the office of Governor, whether he desires to be pensioned under the provisions of section 1 and section 3 of the Pensions (Governors of Dominions, etc.) Act, 1911, or to receive a pension under section 2 of the Pensions (Governors of Dominions, etc.) Act, 1929.