A Developer must re-implement the business logic for an order fulfilment system. The business logic has to make requests to multiple vendors to decide where to purchase an item. The whole process can take up to a week to complete.
What is the MOST efficient and SIMPLEST way to implement a system that meets these requirements?

A. Use AWS Step Functions to execute parallel Lambda functions, and join the results.
B. Create an AWS SQS for each vendor, poll the queue from a worker instance, and joint the results.
C. Use AWS Lambda to asynchronously call a Lambda function for each vendor, and join the results.
D. Use Amazon CloudWatch Events to orchestrate the Lambda functions.