A user needs to determine whether an Amazon EC2 instance's security (CLF-C02)

Correct answer: C) Use AWS CloudTrail to see if the security group was changed.
AWS CloudTrail is a service that provides event history of your AWS account activity, including actions taken through the AWS Management Console, AWS SDKs, command line tools, and other AWS services. This service helps in tracking user activity and resource usage. Specifically, for monitoring changes to security groups, CloudTrail logs events related to security group modifications, such as creating, modifying, or deleting security groups. By analyzing these logs, a user can identify when and by whom changes to security groups were made.

Here's a step-by-step guide on how to use AWS CloudTrail to check for security group changes:

Access the AWS Management Console and navigate to the CloudTrail service.
Select "Event history" from the CloudTrail dashboard.
Filter the events by the event name related to security groups. For example, you can filter by "CreateSecurityGroup", "AuthorizeSecurityGroupIngress", "RevokeSecurityGroupIngress", "DeleteSecurityGroup", etc.
Set the time range to the last month to narrow down the events to the desired period.
Review the list of events to see if there were any changes made to the security groups during the specified time frame.
This method allows the user to see if a change was made to the security groups of an Amazon EC2 instance in the last month, providing visibility into the security posture and changes made to AWS resources.