Final answer:
To access the Notification Center in the xFi web portal, one should click on the 'Notifications' section in the main menu.
Step-by-step explanation:
The correct way to access the Notification Center in the xFi web portal is by clicking on the "Notifications" section in the main menu. Therefore, the answer to your question is A. Click on the "Notifications" section in the main menu. To do this, you'd typically log into the xFi web portal using your credentials, and the main menu, often represented with a list of options or a hamburger icon, should have a section specifically labeled 'Notifications'. Once you click on this, you should be able to see all the notifications related to your account and services.