Which IAM permissions should the developer request for the Lambda function to achieve this functionality?

Explanations:

This option includesdynamodb:DeleteItem, which is unnecessary for retrieving or updating an item. The required permissions are for getting and putting items, not deleting them.

This option includesdynamodb:UpdateItem, but it also includesdynamodb:DescribeTable, which is not needed for retrieving or updating an item.DescribeTabledoes not facilitate item manipulation.

This option includesdynamodb:GetRecords, which is not a valid DynamoDB operation. The correct permissions for the desired functionality do not include this non-existent action. Additionally,dynamodb:UpdateTableis irrelevant to item-level operations.

This option includesdynamodb:GetItemto retrieve the item,dynamodb:PutItemto create or replace the item, anddynamodb:UpdateItemto update attributes of the item if it already exists. These permissions are all necessary for the specified functionality.