(a) whose services are being, immediately before the notified date, utilised by the Trust under sub- section (2), or

(b) whose services, having been made available to the Trust, stand, immediately before the notified date, deputed by the Trust to any other organisation, shall, on and from the notified date, be deemed to be appointed by the Trust under sub- section (1) on the same salary, emoluments and other terms and conditions of service to which he was entitled immediately before the notified date: Provided that every member of the staff aforesaid may, before the expiry of a period of eighteen months from the notified date, elect to go back to the Reserve Bank by exercising an option in writing to that effect, the option once exercised being final, and on the exercise of such option, the Reserve Bank shall, before the expiration of a period of thirty months from the notified date, take back such member of the staff and on such member being taken back by the Reserve Bank, he shall become a member of the staff of the Reserve Bank and shall cease to be a member of the staff of the Trust.