Correct answer - "CloudWatch Event Rules" : Amazon CloudWatch Events is a web service that
monitors your AWS resources and the applications you run on AWS. You can use Amazon CloudWatch
Events to detect and react to changes in the state of a pipeline, stage, or action. Then, based
on rules you create, CloudWatch Events invokes one or more target actions when a pipeline,
stage, or action enters the state you specify in a rule.
"SNS" - Its a service that allows you to send notifications
"SQS" - A message queue service which allows you to decouple your system