NIPOST stands for Nigerian Postal Service, which is responsible for the delivery of mail and other postal services in Nigeria. Therefore, the function of NIPOST is to provide postal services such as sending and receiving letters, parcels, and documents both domestically and internationally. One of the specific functions of NIPOST is issuing money orders, which allows for the transfer of money from one location to another. This service is often used by people who do not have access to bank accounts or other electronic transfer options. Therefore, the correct option is: Issuing money order.