What is the purpose of a control plane node in a Cisco SD-Access network fabric?

What is the purpose of a control plane node in a Cisco SD-Access network fabric?

A. to maintain the endpoint database and mapping between endpoints and edge nodes B. to detect endpoints in the fabric and inform the host tracking database of EID-to-fabric-edge node bindings C. to identify and authenticate endpoints within the network fabric D. to act as the network gateway between the network fabric and outside networks