Answer: AWS Cost and Usage reports

## Explanation AWS Cost and Usage Reports (also known as AWS Cost Explorer) is the correct service for viewing detailed billing activity that occurred 3 months ago. Here's why: - **AWS Cost Explorer** provides access to up to 13 months of historical cost and usage data - It allows customers to analyze their AWS spending patterns over time - For Amazon EC2 specifically, it shows detailed billing information including instance types, regions, and usage patterns **Why the other options are incorrect:** - **A. Amazon EC2 dashboard**: This shows operational metrics and instance status, not detailed billing history - **C. AWS Trusted Advisor dashboard**: This provides cost optimization recommendations and best practices, but not detailed historical billing data - **D. AWS CloudTrail logs**: These contain API activity logs for security and compliance purposes, not billing information As mentioned in the AWS documentation, Cost Explorer is a free tool that allows viewing cost data for up to the last 13 months, making it perfect for analyzing billing activity from 3 months ago.

Author: Ritesh Yadav