Answer:
A authorized official
Step-by-step explanation:
An authorized official is granted legal access to your medicare Enrollemet Application to make changes and updates, you will need to fill out the application (signature is really important), that is where your application is viewed and sent to an MAC (Medicare Administrative Contractor) and then your MAC will give it to someone else, and that someone else is granted access, i believe.
Your MAC is a submits the application, you will find him when you fill out your application as a guide i believe.