Which AWS service monitors AWS accounts for security threats? (CLF-C02)

Correct answer: A. Amazon GuardDuty.
Amazon GuardDuty is an AWS service that provides continuous security monitoring for your AWS accounts and workloads. It analyzes and processes data from various AWS services and sources to detect potential security threats, such as unusual API calls, unauthorized deployments, and potentially compromised EC2 instances.

The other options are not the correct answer:
B. AWS Secrets Manager is a service for securely storing and managing sensitive data, such as passwords, API keys, and database credentials.
C. Amazon Cognito is an AWS service that provides user authentication, authorization, and user management for web and mobile applications.
D. AWS Certificate Manager (ACM) is a service that provides SSL/TLS certificates for use with AWS services.

None of these other services are responsible for monitoring AWS accounts for security threats. That is the primary function of Amazon GuardDuty.