What should an Experience Cloud consultant recommend so that UC’s can log in to CK;s site?

Universal Containers (CU) has been using Salesforce to manage its sales and service processes. UC also an Experience Cloud site to interact with its customers. UC has now acquired Cloud Kicks (CK) Retail to grow its business, CK also uses Salesforce and a self-service site built on the experience Cloud to allow its customers to log support requests. UC now wants its customers to be able to use CK’s self-service site so they can have a more integrated experience.

What should an Experience Cloud consultant recommend so that UC’s can log in to CK;s site?
A . Create separate user account for UC customer in CK’s Experience Cloud site, since SSO cannot be established between two Experience Cloud sites.
B. Use a third-party identity provider to establish SSO between the two Experience Cloud sites, since Salesforce can only be used as a service provider.
C. Establish SSO between the two Experience Cloud sites by using one org as an identity provider and the other org as a service.
D. Create custom Apex handlers using login method from site class to sign in users from one community to the other.

Answer: C