A company’s Amazon EC2 instance with high CPU utilization is a t3.

As described in the AWS Cloud Operations and EC2 Management documentation, changing an instance type (e.g., from T3 to C5) requires that the instance be stopped first. Once stopped, the engineer can modify the instance type through the AWS Management Console, CLI, or API, then start the instance again to apply changes.

This process preserves the root volume, networking configuration, and data, making it an operationally safe and efficient way to upgrade to a different instance family.

Changing the instance type while running (Option D) is unsupported. VM Import/Export (Option A) is for external VM migration. Hibernation (Option B) does not apply to type changes.

Thus, Option C is correct — stopping the instance, changing its type, and restarting it meets AWS best practices.