An administrator needs to configure an existing Amazon Aurora instance as a data store for EC2. Which solution should be implemented to minimize write operation latency?

Creating a read replica in the same subnet is the best solution to minimize write operation latency for an existing Amazon Aurora instance used as a data store for EC2. When a read replica is created in the same subnet, it can share low-latency network connections with the primary instance, which facilitates faster data access and reduces the time needed for write operations due to shortened round-trip communication times.

This setup is particularly effective because data can be replicated synchronously or asynchronously between the primary instance and the read replica, allowing for quicker reads from the replica while allowing the primary instance to handle write operations more efficiently. As a result, this configuration ensures that the application can maintain high performance with minimal delays, thus providing a smoother user experience.

Other solutions, such as implementing a multi-region deployment or a Multi-AZ Zone, can enhance availability and fault tolerance but may introduce additional latency due to geographic distance or the overhead of managing state across multiple zones. Creating a read-only replica in another Availability Zone shares similar concerns regarding latency as it could be in a different zone, potentially adding additional hops in the communication path. Therefore, the option to create a read replica in the same subnet provides the best balance of performance and efficiency for minimizing write operation latency.