A Python AWS Lambda function is triggered by S3 object-creation events; it reads from S3 and writes to a DynamoDB table. The function executes on invocation but fails when attempting to write to DynamoDB. What is the MOST likely cause?

The most likely cause for a Lambda function failing to write to DynamoDB is insufficient permissions. AWS services operate on the principle of least privilege, meaning the Lambda function's execution role must explicitly grant dynamodb:PutItem (or similar write actions) permissions to the target DynamoDB table. Without these permissions, the write operation will be denied. Incorrect options: Concurrency limits typically prevent the function from invoking or cause throttling errors, not permission-related write failures once invoked. DynamoDB write operations do not inherently require a GSI; GSIs are for optimizing query patterns, not for basic write functionality. DynamoDB is a regional service, and its tables are replicated across multiple Availability Zones within a region. The physical location of a Lambda function within an AZ relative to a DynamoDB table's underlying infrastructure does not cause permission errors.