A developer is creating a serverless ecommerce application that is based on AWS Lambda. An asynchronous workflow manages the checkout process and must orchestrate different Lambda functions.
The workflow runs one function for each item in the shopping cart. The developer is using AWS Step Functions to orchestrate the process.
The checkout process is running the Lambda functions serially, and the developer needs to improve the performance of the process.
What should the developer do to meet these requirements?

A. Use a Choice state to identify the size of the cart and invoke a specific Lambda function with the entire cart content.
B. Use a Retry field for a second run to process all the items that failed.
C. Use a Parallel state to iterate over all the items in parallel.
D. Use a Map state to iterate over all the items in the cart.