You are developing a mobile application that allows users to create and manage to-do lists. Your application has the following requirements:
• Store and synchronize data between different mobile devices.
• Support offline access.
• Provide real-time updates on each user's device.
You need to implement a database solution while minimizing operational effort. Which approach should you use?

A. Create a Cloud SQL for MySQL instance. Implement a data model to store to-do list information. Create indexes for the most heavily and frequently used queries. B. Create a Bigtable instance. Design a database schema to avoid hotspots when writing data. Use a Bigtable change stream to capture data changes. C. Use Firestore as the database. Configure Firestore offline persistence to cache a copy of the Firestore data. Listen to document changes to update applications whenever there are document changes. D. Implement a SQLite database on each user's device. Use a scheduled job to synchronize each device database with a copy stored in Cloud Storage.