AWS Certified Solutions Architect – Associate (SAA-C03) — Question 878

A company runs an application that stores and shares photos. Users upload the photos to an Amazon S3 bucket. Every day, users upload approximately 150 photos. The company wants to design a solution that creates a thumbnail of each new photo and stores the thumbnail in a second S3 bucket.

Which solution will meet these requirements MOST cost-effectively?

Answer options

• A. Configure an Amazon EventBridge scheduled rule to invoke a script every minute on a long-running Amazon EMR cluster. Configure the script to generate thumbnails for the photos that do not have thumbnails. Configure the script to upload the thumbnails to the second S3 bucket.
• B. Configure an Amazon EventBridge scheduled rule to invoke a script every minute on a memory-optimized Amazon EC2 instance that is always on. Configure the script to generate thumbnails for the photos that do not have thumbnails. Configure the script to upload the thumbnails to the second S3 bucket.
• C. Configure an S3 event notification to invoke an AWS Lambda function each time a user uploads a new photo to the application. Configure the Lambda function to generate a thumbnail and to upload the thumbnail to the second S3 bucket.
• D. Configure S3 Storage Lens to invoke an AWS Lambda function each time a user uploads a new photo to the application. Configure the Lambda function to generate a thumbnail and to upload the thumbnail to a second S3 bucket.

Correct answer: C

Explanation

Triggering an AWS Lambda function via S3 event notifications is the most cost-effective solution because Lambda charges only for compute time used, which is extremely minimal for processing 150 images per day. Running a continuous Amazon EC2 instance or an Amazon EMR cluster would incur significant idle costs. S3 Storage Lens is an analytics tool for monitoring storage usage and cannot be used to trigger event-driven processing of individual object uploads.