How does that server-side component obtain the value for the ‘context’ element?

Refer to the exhibit.

On line 4, the script retrieves a context from a DOM element that was generated from a server-side component.

How does that server-side component obtain the value for the ‘context’ element?
A . by opening a dialog asking the end-user to paste his personal access token
B . by completing an authorization code grant flow using the identifier and secret of an OAuth integration
C . by embedding the access token of a Bot account
D . by creating a guest token using the identifier and secret of a Guest Issuer application

Answer: B