The correct answer is C: Program your radio with the group's ID or code. To join a digital repeater's talkgroup, you need to program your radio with the talkgroup's identification number or code. This is done through your radio's programming software or menu system. Digital repeaters (like DMR, D-STAR, or System Fusion) use talkgroups to organize communications. Each talkgroup has a unique ID number. When you program your radio with a talkgroup ID and transmit, your signal is routed to that talkgroup. Other operators listening to the same talkgroup will hear your transmission. This is similar to selecting a channel on an analog repeater, but uses digital IDs instead.