Which two actions should an Architect recommend UC to take?

Universal Containers (UC) is building an authenticated Customer Community for its customers. UC does not want customer credentials stored in Salesforce and is confident its customers would be willing to use their social media credentials to authenticate to the community.

Which two actions should an Architect recommend UC to take?
A . Use Delegated Authentication to call the Twitter login API to authenticate users.
B. Configure an Authentication Provider for LinkedIn Social Media Accounts.
C. Create a Custom Apex Registration Handler to handle new and existing users.
D. Configure SSO Settings For Facebook to serve as a SAML Identity Provider.

Answer: B,C