Answer: Generate Amazon S3 presigned URLs in the application. Upload files directly from the user's browser into an S3 bucket.

## Explanation **Option C is the most scalable solution** because it uses Amazon S3 presigned URLs to allow direct uploads from users' browsers to S3, bypassing the application servers entirely. ### Why Option C is correct: 1. **Direct upload to S3**: With presigned URLs, users upload files directly to Amazon S3, eliminating the need for application servers to handle file upload traffic. 2. **Automatic scalability**: Amazon S3 automatically scales to handle massive amounts of upload traffic without any provisioning. 3. **Reduced load on application servers**: By offloading file uploads to S3, the application servers can focus on processing business logic. 4. **Cost-effective**: No need to over-provision application servers to handle upload spikes. 5. **High availability**: S3 provides 99.999999999% durability and 99.99% availability. ### Why other options are less scalable: **Option A**: Uploading to application servers first creates a bottleneck - application servers would need to be scaled to handle upload traffic, which is inefficient and expensive. **Option B**: AWS Storage Gateway is designed for hybrid cloud storage, not for direct web uploads at scale. It's not optimized for handling massive concurrent uploads from web browsers. **Option D**: Amazon EFS is a network file system that requires mounting to EC2 instances. Direct browser uploads to EFS are not supported, and even if they were, EFS doesn't scale as automatically or cost-effectively as S3 for this use case. ### Key AWS Services: - **Amazon S3 Presigned URLs**: Time-limited URLs that grant temporary access to upload objects directly to S3 buckets - **Amazon S3**: Object storage service with virtually unlimited scalability and high durability This architecture pattern is commonly used for media uploads, file sharing, and other scenarios requiring scalable file upload capabilities.

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