Answer: Store images in Amazon S3 Standard-Infrequent Access (S3 Standard-IA). Use S3 Standard-IA to directly deliver images by using a static website.

## Explanation **Why Option D is the most cost-effective solution:** 1. **Infrequent Access Pattern**: The question states that "users request each image only once or twice a year." This is a perfect use case for S3 Standard-IA (Infrequent Access), which is designed for data that is accessed less frequently but requires rapid access when needed. 2. **Cost Optimization**: - **S3 Standard-IA** has lower storage costs than S3 Standard but has retrieval fees - For infrequent access (1-2 times per year), the lower storage costs outweigh the retrieval fees - S3 Standard would be more expensive for this access pattern 3. **High Availability**: S3 provides 99.99% availability by default, meeting the requirement for a highly available solution. 4. **Static Website Hosting**: S3 can directly serve static content (images) through static website hosting, eliminating the need for EC2 instances and reducing operational overhead. 5. **Comparison with other options**: - **Option A (EBS + EC2)**: Expensive due to EC2 instance costs, EBS volumes, and requires management overhead - **Option B (EFS + EC2)**: EFS is more expensive than S3 for this use case, plus EC2 costs - **Option C (S3 Standard)**: More expensive storage than S3 Standard-IA for infrequently accessed data **Key AWS Concepts**: - **S3 Storage Classes**: - S3 Standard: For frequently accessed data - S3 Standard-IA: For infrequently accessed data that requires rapid access - S3 Glacier: For archival data with retrieval times of minutes to hours - **S3 Static Website Hosting**: Allows serving static content directly from S3 without web servers - **Cost Optimization**: Matching storage class to access patterns is crucial for cost-effective solutions This solution provides the required high availability while minimizing costs for the given access pattern.

Author: LeetQuiz Editorial Team