Correct answer - "CloudWatch Event Rules + SNS" : You can create a trigger for an AWS CodeCommit
repository so that events in that repository trigger notifications from an Amazon Simple
Notification Service (Amazon SNS) topic. You might want to create a trigger to an Amazon SNS
topic to enable users to subscribe to notifications about repository events, such as the
deletion of branches.
"AWS Lambda" - Lambda does integrate with CodeCommit but for this requirement you don't need to
write custom code so instead SNS and HTTP integration is your solution
"AWS SES" - Simple email service allows for more custom email but for this requirement SNS does
the job
"CodeBuild" - CodeBuild is a code building service and as such it cannot help you with codecommit
notifications