A person who for any reason ceases to be a member of the Central Industrial Security Force does not have to surrender which one of the following items ?

According to Section 17 of the Central Industrial Security Force (CISF) Act, 1968, any person who ceases to be a member of the Force must immediately surrender several items to the authorities. These specifically include the certificate of appointment, arms, accoutrements, clothing, and any other articles that were furnished to them for the performance of their official duties. An appreciation letter is a personal recognition of service or merit and is not considered an official article or piece of equipment that must be returned to the government upon leaving the service. Therefore, it is the only item among the options that the individual is permitted to retain.