Final answer:
To have an official RBT supervisor, both additional training in supervision and being listed on the BACB registry as your supervisor are required.
Step-by-step explanation:
In order for your supervisor at an agency to serve as your official RBT supervisor, both options A and B must be fulfilled.
Option A states that the supervisor must have additional training in supervision.
Option B states that the supervisor must be listed on the BACB registry as your supervisor. This registry ensures that the supervisor meets the requirements to provide appropriate supervision.