Comprehensive and Detailed 150 to 200 words of Explanation From Google Cloud DevOps guides documents:

To maintain a secure software supply chain, Google Cloud recommends enabling On-Demand Scanning and Continuous Analysis via the Artifact Analysis API. For Artifact Registry, you should enable automatic scanning, which scans images immediately upon upload. Crucially, your requirement asks for continuous scanning of existing images. Google Cloud’s Continuous Analysis does exactly this: it monitors vulnerability databases (like the CVE list) and automatically re-scans images stored in Artifact Registry whenever new threats are discovered. This ensures that an image that was "clean" last week is flagged immediately if a new zero-day vulnerability is identified today.

To address the requirement of tracking who pushed each image, Cloud Audit Logs is the standard tool. Every action in Artifact Registry, such as v1.repositories.images.create or v1.repositories.dockerImages.import, is recorded as an Administrative Write event. By inspecting these logs, security teams can identify the specific identity (service account or user email) associated with the push event. This combination of Continuous Analysis for threat detection and Cloud Audit Logs for traceability provides a robust security posture, minimizing administrative overhead compared to manual scripting or external storage solutions (Option D).