Final answer:
Customers are able to perform rate plan changes, check usage, make payments and more using their myAT&T account.
Step-by-step explanation:
The correct answer is A) myAT&T account. Customers can perform rate plan changes, check usage, make payments, and more using their myAT&T account. This online account allows customers to manage their AT&T services and access various features and functions.
Learn more about myAT&T account