Which service should you recommend to complete the design?

A customer uses Azure to develop a mobile app that will be consumed by external users as shown in the following exhibit.

You need to design an identity strategy for the app.

The solution must meet the following requirements:

• Enable the usage of external IDs such as Google, Facebook, and Microsoft accounts.

• Be managed separately from the identity store of the customer.

• Support fully customizable branding for each app.

Which service should you recommend to complete the design?
A . Azure Active Directory (Azure AD) B2C
B . Azure Active Directory (Azure AD) B2B
C . Azure AD Connect
D . Azure Active Directory Domain Services (Azure AD DS)