You're tasked with storing millions of files that will be frequently accessed by Cloud Functions. What storage architecture should you use?

*Explanation:* For storing millions of files frequently accessed by Cloud Functions, the best architecture is to use Multi-Regional Cloud Storage with Pub/Sub notifications. This configuration provides high availability and integrates directly with Pub/Sub for efficient handling of file access events. Other options such as Regional Persistent Disk, Cloud Filestore, Nearline Cloud Storage, or Standard Cloud Storage with Object Versioning and Pub/Sub notifications may not offer the same level of performance, scalability, and integration for this use case.