You need to alert when free disk space on EC2 instances with attached EBS volumes falls below a threshold, but only if EBS DiskReadOps is also above a threshold. You already have an Amazon SNS topic for notifications. How can you ensure a notification is sent only when both conditions are true?

The CloudWatch agent is necessary to collect custom metrics like free disk space from within the EC2 instance. Once these metrics are collected, individual CloudWatch metric alarms can be created for both disk space and DiskReadOps. A composite alarm then combines these two metric alarms, allowing you to specify that a notification should be sent via the SNS topic only when both conditions (disk space below threshold AND DiskReadOps above threshold) are met. The second option is incorrect because it would send two separate notifications if both conditions were met, rather than a single notification based on their combined state. The third option is incorrect because EBSByteBalance% is not a standard CloudWatch metric and does not represent free disk space. The fourth option is incorrect because detailed monitoring provides more frequent data for standard metrics but does not collect internal disk space metrics, which still require the CloudWatch agent.