Which solution will meet these requirements?

Explanations:

This option requires rewriting the application code to stream logs directly to SNS, which is not practical for log management and would add unnecessary complexity. SNS is not designed to handle log streaming directly, and this approach does not leverage existing AWS services effectively.

A subscription filter on a CloudWatch Logs log group is used for real-time processing of log data, but it does not have the capability to evaluate the number of error messages over a defined period (e.g., 5 minutes) to trigger notifications. It can send notifications for specific log entries but not based on counts over time.

Amazon Inspector is primarily a security assessment service and does not monitor application errors within logs. It does not provide functionality to send SNS notifications based on log error counts. This approach would not fulfill the requirement for monitoring application errors in logs.

This option creates a CloudWatch metric filter to extract error messages from the log data and generate a custom metric based on these errors. A CloudWatch alarm can then be set on this custom metric to trigger an SNS notification when the error count exceeds the defined threshold within a specified 5-minute period, meeting the requirements efficiently.