Which combination of steps should the SysOps administrator take to meet this requirement?

Explanations:

An Amazon EventBridge rule cannot directly monitor CloudWatch metrics like FreeStorageCapacity. Instead, CloudWatch alarms are the appropriate mechanism to trigger notifications based on specific metric thresholds.

Creating a CloudWatch alarm for the FreeStorageCapacity metric allows the administrator to monitor the available storage. Setting the alarm to trigger when the capacity falls below 100 GB (100,000,000,000 bytes) will help in sending notifications through the SNS topic when the alarm enters ALARM state.

While a Lambda function could be used to publish notifications, it is unnecessary in this scenario. The CloudWatch alarm can directly publish to the SNS topic, making this additional step redundant.

An Amazon EventBridge rule is not required for this use case since the CloudWatch alarm can directly notify the SNS topic. Thus, configuring an EventBridge rule for this purpose is not the correct approach.

Configuring the CloudWatch alarm action to publish to the SNS topic when the alarm enters ALARM state directly fulfills the requirement to notify the SysOps administrator when the file system’s available storage drops below 100 GB.