The correct answer is C, AWS Artifact. AWS Artifact is a service provided by Amazon Web Services that allows users to access and download various security and compliance reports about the AWS infrastructure. These reports include compliance reports such as SOC (Service Organization Control) reports, ISO certifications, and PCI DSS (Payment Card Industry Data Security Standard) reports, as well as AWS service-specific documents like AWS Terms of Service and Data Processing Addendums. AWS Artifact centralizes the distribution of these reports, making them easily accessible to customers who require evidence of AWS compliance with various industry standards and regulations. Users can access AWS Artifact through the AWS Management Console to search for and download the desired reports. The other options, Amazon GuardDuty, AWS Security Hub, and AWS Shield, are related to security and compliance but do not provide the on-demand access to compliance reports as AWS Artifact does.