Design a Node.js mobile news-feed database that provides zonal resiliency by default, low latency, ACID semantics, optional middle tier, semi-structured storage, and client libraries that tolerate network partitions and offline mode.

Firestore is the best choice because it offers zonal resiliency by default, ensuring high availability. Its NoSQL document model provides flexible, semi-structured storage suitable for news feed data. Firestore guarantees ACID transactions, crucial for data integrity. It's a serverless, fully managed database, eliminating the need for a middle tier. Crucially, Firestore client libraries are designed for mobile and web applications, offering offline data persistence and automatic synchronization, which tolerates network partitions and supports offline mode. Bigtable is a wide-column store, optimized for analytical workloads, not ideal for ACID transactions or offline mobile access. Cloud SQL is a relational database; while it offers ACID, its schema rigidity and lack of native offline mobile support make it less suitable. BigQuery is an analytical data warehouse, not designed for transactional mobile applications or low-latency individual record access.