Explanation

Amazon RDS with Multiple Availability Zones provides high availability and fault tolerance by:

• Automatic failover: If the primary database instance fails, RDS automatically fails over to the standby replica in a different Availability Zone
• Data redundancy: Synchronous replication ensures data consistency across Availability Zones
• Fault tolerance: Protects against AZ-level failures and infrastructure issues
• High availability: Maintains database availability even during maintenance events

Why other options are incorrect:

• Single Availability Zone: Only provides a single instance with no automatic failover capability
• RDS snapshots: Used for backup and restore, not for high availability
• AWS DMS: Used for database migration, not for providing high availability

For PostgreSQL databases requiring high availability and fault tolerance, Amazon RDS Multi-AZ deployment is the recommended solution.