You’ve accidentally lost the administrator password for an EBS-backed Windows Server EC2 instance. The instance has the Systems Manager agent installed. You want to regain access to your instance. What is the easiest way to resolve this issue?

Answer options:

A.Use Systems Manager Run Command to run AWSSupport-RunEC2RescueForWindowsTool command document.
B.Open Amazon EC2 console. Under Instances, select the specific instance. Under Actions, Instance Settings, choose the Reset Instance Password option.
C.Generate a new key pair. Use Import-EC2KeyPair AWS Tools for Windows PowerShell command.
D.Use EC2Rescue Tool. Choose Diagnose and Rescue. Select Ec2SetPassword.

Answer: A
Option A is CORRECT because using the SSM run command to run the AWSSupport-RunEC2RescueForWindowsTool command document with the ResetAccess command is the easiest way to reset a lost Windows Server password.
Option B is incorrect because there is no Reset Instance Password option under Actions, Instance Settings.
Option C is incorrect because the Import-EC2KeyPair command imports a key pair into the AWS EC2 Console and is not used to reset the password for a windows machine.
Option D is incorrect because it is not the easiest and quickest solution. This option requires provisioning of a recovery Windows Server EC2 instance, installing EC2Rescue Tool, and manually resetting the password.
Reference:
https://aws.amazon.com/premiumsupport/knowledge-center/reset-admin-password/