Selected Answer: A "only if a user uploads data to an Amazon S3 bucket" that rules out B & C because we need s3:ObjectCreated:* You don't need SNS for S3 event notifications, so A is simpler.

A. Create an S3 event notification that uses an event type of s3:ObjectCreated:*. Add a filter rule to send notifications only when the suffix contains .csv. Set the Amazon Resource Name (ARN) of the Lambda function as the target for the event notification. Explanation: This option directly triggers the Lambda function only when a .csv file is uploaded to the S3 bucket, which minimizes unnecessary Lambda invocations. It uses a specific event type (s3:ObjectCreated:*) and a filter rule to make sure the Lambda function is invoked only for relevant events. In addition, it calls the Lambda function directly without needing extra services like Amazon SNS, which lowers operational overhead.

Selected Answer: A "You can use Lambda to process event notifications from Amazon Simple Storage Service. Amazon S3 can send an event to a Lambda function when an object is created or deleted" https://docs.aws.amazon.com/lambda/latest/dg/with-s3.html

Selected Answer: A S3 event notification to lamba for file prefix with.csv is the least overhead way

Selected Answer: A since it is the least operational, D is a candidate, but it adds a SNS operation, which in this case is not needed. so A includes S3 and triggering toward the lambda function. 2 services.

Selected Answer: A A is the answer for least operational. C is also correct!

Selected Answer: A s3:ObjectCreated:* instead of s3:*: triggers the Lambda function only when objects are created in the bucket.

Selected Answer: A A is correct. SNS is pointless in this scenario and it adds another layer of complexity

Selected Answer: A A makes the most sense. B and C are just wasting resources. Why run a function when we only want it to run when an object is created. D: No need for an SNS topic.