What type of identification will customers use for their portal registration?

Answer options:

A.Register for a new local environment
B.Register using an external account
C.Redeem invitation
D.Register using Azure AD account

Correct Answer: B 
LiveSafe customers should use their social login to register at the company`s portal. They need to use credentials from third-party identity providers like Microsoft, Twitter, Facebook, Google, etc., for the registration. 
Power Apps portal provides two methods of registration: Local authentication — creates a local identity with a username and password stored in a Dataverse database internally.
External authentication — uses credentials of the third-party identity providers, like OAuth2 (Microsoft, Twitter, Facebook, Google, etc.), OpenID (Azure AD, Azure AD B2C), and WS-Federation and SAML 2.0 (AD on-premises).
Portal administrators can enable/disable Identity providers and set them as default on the portal’s Authentication Settings panel. 
For each authenticated user, a portal creates a contact record in the Dataverse database. It also assigns a web role. The role defines a user`s access to portal resources. 
All other options are incorrect. 
For more information about Power Apps portal authentication, please visit the below URLs: 

https://docs.microsoft.com/en-us/learn/modules/power-apps-architecture/7-portals
https://docs.microsoft.com/en-us/learn/modules/introduction-power-apps-portals/06-overview-portals-security