(b) every officer or other employee in respect of whom an order of transfer under sub- section (1) may be made after the appointed day shall, within six months from the date or such order, exercise his option under sub- section (4), and in each such case such option once exercised shall be final: Provided that where an officer or other employee having exercised an option under sub- section (4) before the appointed day--
(i) has died or retired before the appointed day, or dies or retires after the appointed day, before exercising the option as required by this sub- section, or
(ii) does not exercise the option as required by this sub- section, the option already exercised by him shall be deemed to have been validly exercised by him under sub- section (4).