Which AWS solution should the company use to meet these requirements?

Explanations:

A single Availability Zone does not provide high availability or fault tolerance because it relies on one data center. If that Availability Zone fails, the database will be unavailable.

RDS snapshots are used for backups and data recovery, not for providing high availability or fault tolerance in real-time operation.

Amazon RDS with multiple Availability Zones (Multi-AZ) provides high availability and fault tolerance by automatically replicating data to a standby instance in a different Availability Zone. If one zone fails, the system fails over to the standby.

AWS Database Migration Service (DMS) is used for migrating databases to AWS, not for providing high availability or fault tolerance for an operational database.