Answer: Create a report in Cost Explorer and download the report.

## Explanation **Correct Answer: B - Create a report in Cost Explorer and download the report.** **Why this is correct:** 1. **Cost Explorer** is specifically designed for cost analysis and reporting in AWS. It provides detailed cost and usage data that can be filtered, grouped, and analyzed. 2. Cost Explorer allows you to create custom reports that can be organized by various dimensions, including: - Service - Linked account - **Usage type** - **Tags** (which can include user/department tags) - Region - API operation 3. You can download these reports in CSV format for further analysis and budget planning. 4. Cost Explorer provides granular cost data that can be broken down to show costs by user if proper tagging is implemented. **Why the other options are incorrect:** **A. Run a query with Amazon Athena to generate the report.** - While Athena can query cost and usage data stored in S3, this requires setting up AWS Cost and Usage Reports (CUR) to S3 first, which is more complex. - This approach is better for advanced analytics but not the "most efficient" way for a simple user-based cost report. **C. Access the bill details from the billing dashboard and download the bill.** - The billing dashboard provides high-level invoice information but lacks the granular, user-level detail required. - Standard AWS bills don't break down costs by individual users unless specific tagging and account structures are in place. **D. Modify a cost budget in AWS Budgets to alert with Amazon Simple Email Service (Amazon SES).** - AWS Budgets is for setting cost thresholds and alerts, not for generating detailed cost reports by user. - This solution would only send alerts when costs exceed thresholds, not provide the comprehensive report needed for budget planning. **Key Considerations:** - For accurate user-based reporting, ensure proper tagging of AWS resources with user/department tags. - Enable AWS Cost Explorer in the AWS Management Console. - Use Cost Explorer's filtering and grouping capabilities to create reports by tag values (e.g., "user" tag). - Schedule regular report exports for ongoing budget planning. This solution provides the most efficient, out-of-the-box approach to obtain user-level cost data for department budget planning.

Author: LeetQuiz Editorial Team