What are the two recommended actions UC can take to achieve this Functionality?

Universal Containers (UC) would like its community users to be able to register and log in with Linkedin or Facebook Credentials. UC wants users to clearly see Facebook &Linkedin Icons when they register and login .

What are the two recommended actions UC can take to achieve this Functionality? Choose 2 answers
A . Enable Facebook and Linkedin as Login options in the login section of the Community configuration.
B . Create custom Registration Handlers to link Linkedin and facebook accounts to user records.
C . Store the Linkedin or Facebook user IDs in the Federation ID field on the Salesforce User record.
D . Create custom buttons for Facebook and inkedin using JAVAscript/CSS on a custom Visualforce page.

Answer: A,B