Which of the below mentioned options is not a valid IAM username?

An organization is trying to create various IAM users.

Which of the below mentioned options is not a valid IAM username?
A . John.cloud
B . john@cloud
C . John=cloud
D . john#cloud

Answer: D

Explanation:

AWS Identity and Access Management is a web service which allows organizations to manage users and user permissions for various AWS services. Whenever the organization is creating an IAM user, there should be a unique ID for each user. The names of users, groups, roles, instance profiles must be alphanumeric, including the following common characters: plus (+., equal (=., comma (,., period (.., at (@., and dash (-..