Correct answer - "CloudWatch" : CloudWatch helps only with metrics monitoring. The other AWS
services are relevant in helping you debug authorization exceptions.
Incorrect:
"IAM" - You can check your permissions here and make sure they are set properly
"CloudTrail" - This service logs API calls and can help you find out what is going
"STS" - Using sts decode-authorization-message, you are able to get more information
about authorization exceptions happening with the CLI.