Correct Answer: A
AWS Detective is a persistent machine learning-driven service that automatically collates log data from all AWS resources. This log data is then applied into machine learning algorithms to derive data patterns between AWS services and resources, graph theory and statistical analysis. This information allows the user to proactively visualize their AWS environment from a security standpoint, thereby allowing them to quickly and efficiently conduct security investigations when they occur.
https://docs.aws.amazon.com/detective/latest/adminguide/what-is-detective.html
Option B is INCORRECT because AWS Macie primarily matches and discovers sensitive data such as personally identifiable information (PII) but does not have the capability to keep track of data behaviors between AWS services to detect anomalies. Therefore the service does not meet the requirement.
Option C is INCORRECT because AWS Shield is a Distributed Denial of Service (DDoS) protection service that applies to applications running in the AWS environment. The service does not have machine learning capability to keep track of data behaviors between AWS services.
Option D is INCORRECT because Amazon CloudWatch Anomaly Detection is a machine learning feature limited to Amazon CloudWatch metrics. It does not extend to all the AWS services, so it does not meet the requirement.