The suggested answer is A, D.
The first table listed in a RIB group configuration is the primary route table and determines the address family of the RIB group. This means that the primary route table is pivotal in defining the nature of the address family. A RIB group must contain one or more import-rib statements to specify the secondary route tables that will receive routes from the primary table. These import-rib statements are essential for the functioning of the RIB group as they define the routing tables that will be updated with the routes.