A company is developing an internal cost-estimation tool that uses an ML model in Amazon...

This use case involves large payloads (high-resolution images), variable processing time, and a requirement to notify users upon completion. AWS documentation recommends Amazon SageMaker asynchronous inference for exactly this scenario.

Asynchronous inference allows clients to submit inference requests without waiting for a response. The request payload is stored in Amazon S3, and the inference result is written back to S3 when processing is complete. This approach is designed for workloads that cannot meet real-time latency requirements and where payload sizes exceed real-time limits.

SageMaker asynchronous inference integrates natively with Amazon SNS to send notifications when inference completes or fails, which directly satisfies the user notification requirement.

Batch transform jobs are intended for offline, scheduled processing of large datasets and do not provide built-in user notification mechanisms. Amazon EFS is not required because SageMaker natively integrates with S3 for inference input and output.

AWS explicitly documents asynchronous inference as the preferred solution for large image inference with completion notifications.

Therefore, Option B is the correct and AWS-verified answer.