Which AWS service can be used to meet this requirement?

Explanations:

AWS Service Catalog is used for creating and managing catalogs of IT services that are approved for use on AWS. It does not track changes or modifications to EC2 instances.

AWS Config provides a detailed history of the configuration of AWS resources, including EC2 instances. It records and evaluates configurations and changes, allowing users to review modifications over time.

Amazon CloudWatch is primarily a monitoring service that provides data and insights on the performance and operational health of AWS resources, but it does not track configuration changes or modifications to EC2 instances.

AWS Artifact is a service that provides on-demand access to AWS compliance documentation and reports. It does not provide functionality for tracking or reporting on changes made to EC2 instances.