What Automation Studio Activity sequence should be used to ensure the appropriate subscribers are unsubscribed from the All Subscriber List?

Northern Trail Outfitters receives a nightly encrypted unsub file to their Marketing Cloud SFTP from a third-party email platform. These files are used to unsubscribe existing subscribers. They do not use Email Address as Subscriber Key.

What Automation Studio Activity sequence should be used to ensure the appropriate subscribers are unsubscribed from the All Subscriber List?
A . Import File > Data Extract > File Transfer > Import File
B . File Transfer > Import File > Query > Data Extract > File Transfer > Import File
C . Import File > Query > Data Extract > File Transfer > Import File
D . File Transfer > Import File > Data Extract > File Transfer > Import File

Answer: B