Which tasks require use of the AWS account root user?

Explanations:

Changing an AWS Support plan requires the root user because it involves billing and account-level permissions.

Modifying an EC2 instance type can be done by an IAM user with the necessary EC2 permissions; root access is not required.

Grouping resources in AWS Systems Manager can be done by an IAM user with appropriate permissions.

Running applications in Amazon EKS can be managed by IAM users with the right roles; root access is unnecessary.

Closing an AWS account is a sensitive action that only the root user can perform.