A company uses AWS Organizations and needs a consolidated list of all EC2 instances across accounts that show underutilized CPU or memory, along with recommendations for downsizing those instances. Which solution achieves this with the LEAST effort?

The correct solution leverages AWS Cost Explorer's resource optimization recommendations, which are designed to identify underutilized resources and suggest downsizing. By retrieving these recommendations from the organization's management account, you gain a consolidated view across all member accounts, fulfilling the requirement for a single list with the least effort. Deploying the CloudWatch agent via Systems Manager ensures the necessary metrics (including memory, which isn't a default EC2 metric) are collected for Cost Explorer to analyze. The incorrect options involve more manual or complex steps. Installing a third-party product or creating custom Lambda functions, S3 storage, and Athena queries adds significant development and maintenance overhead. Retrieving recommendations from each member account individually would be more cumbersome than using the consolidated view from the management account.