Final answer:
The Sexual Assault Response Coordinator (SARC) must serve as the co-chair of the sexual assault Case Management Group (CMG).
Step-by-step explanation:
The individual who must serve as the co-chair of the sexual assault Case Management Group (CMG) is the Sexual Assault Response Coordinator (SARC). The CMG is a multidisciplinary group that is responsible for coordinating the response to sexual assault incidents and ensuring the provision of care and support to victims. The SARC plays a crucial role in this group, working alongside others, such as medical personnel, legal staff, and victim advocates, to ensure a comprehensive and cohesive response.