The correct answer is: Create an HTTPS endpoint using Amazon API Gateway. Configure it to trigger an AWS Lambda function that processes incoming messages and stores the results in Amazon DynamoDB.

This architecture is highly available, serverless, and scalable. Amazon API Gateway easily creates a managed HTTPS endpoint, which is ideal for receiving messages from the badge readers. It automatically handles traffic spikes, and when paired with AWS Lambda, provides an event-driven compute layer without provisioning infrastructure. Lambda can immediately process the badge messages and store the results in Amazon DynamoDB, which is a fully managed, low-latency NoSQL database well-suited for rapid access and analysis by the security team.

The option Use Amazon Route 53 to route badge reader messages directly to a Lambda function is not valid because Route 53 does not natively route HTTP or HTTPS traffic to Lambda functions. It is a DNS service, not an HTTPS endpoint provider, and cannot serve as the front door for REST-style APIs or sensor-based HTTPS traffic.

The option Provision an EC2 instance to act as the HTTPS endpoint and handle processing is less operationally efficient. While functional, it introduces single points of failure and increases maintenance burden for patching, scaling, and security hardening. It does not offer the automatic scalability and managed capabilities of the API Gateway + Lambda model.

The option Establish a Site-to-Site VPN to a VPC and use a gateway VPC endpoint for S3 is overly complex and not well-suited for real-time HTTPS-based event ingestion. S3 is not designed for direct HTTPS input from external devices without an intermediate processing layer, and this approach lacks flexibility for parsing and storing structured results for querying.

This question is important because it tests knowledge of modern, event-driven, and serverless design patterns in AWS. A key takeaway is that API Gateway + Lambda is often the best answer for ingesting data from external sources over HTTPS, especially when combined with DynamoDB for persistence and retrieval.

A helpful trick is to look for terms like 'HTTPS endpoint,' 'highly available,' and 'scalable'these are clues that point toward API Gateway and Lambda, which handle these requirements with minimal operational overhead.

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