A company is running a critical application that uses an Amazon RDS for MySQL database...

Migrate the database to Amazon Aurora MySQL. - Create an Amazon Aurora Replica. - Use RDS Proxy in front of the database. - These options are correct because they address the requirement of reducing the failover time to less than 20 seconds. Migrating to Amazon Aurora MySQL and creating an Aurora replica can reduce the failover time to less than 20 seconds. Aurora has a built-in, fault-tolerant storage system that can automatically detect and repair failures. Additionally, Aurora has a feature called "Aurora Global Database" which allows you to create read-only replicas across multiple AWS regions which can further help to reduce the failover time. Creating an Aurora replica can also help to reduce the failover time as it can take over as the primary DB instance in case of a failure. Using RDS proxy can also help to reduce the failover time as it can route the queries to the healthy DB instance, it also helps to balance the load across multiple DB instances.