A ticketing service runs on Linux EC2 instances in an Auto Scaling group. The service reads a pricing file stored in an S3 bucket (S3 Standard). A third‑party central pricing system updates the pricing file every 1–15 minutes; the file has several thousand line items. Each EC2 instance downloads the file at launch, but instances sometimes use stale pricing, causing incorrect customer charges. Which solution will solve this problem MOST cost‑effectively?

Mountpoint for Amazon S3 allows EC2 instances to access S3 objects as a local file system, ensuring they always read the latest version of the pricing file directly from S3. This eliminates stale data issues cost-effectively because there are no additional services or data synchronization mechanisms required. Using a Lambda function to update DynamoDB would introduce additional cost for DynamoDB reads and writes, and requires rewriting the ticketing service logic to query a database instead of reading a file. A Lambda function updating EFS would incur EFS storage and throughput costs, and EFS is not designed for frequent, small file updates from an external source like S3 in this manner. EBS Multi-Attach is not suitable here as it requires all instances to be in the same Availability Zone, and managing file updates across multiple instances on an EBS volume would be complex and error-prone, potentially leading to data inconsistencies.