How can the Architect meet these requirements?

Universal Containers (UC) is building a customer community and will allow customers to authenticate using Facebook credentials. The First time the user authenticating using facebook, UC would like a customer account created automatically in their Accounting system. The accounting system has a web service accessible to Salesforce for the creation of accounts .

How can the Architect meet these requirements?
A . Create a custom application on Heroku that manages the sign-on process from Facebook.
B . Use JIT Provisioning to automatically create the account in the accounting system.
C . Add an Apex callout in the registration handler of the authorization provider.
D . Use OAuth JWT flow to pass the data from Salesforce to the Accounting System.

Answer: C