Correct answer - "S3" : If you upload a local template file, AWS CloudFormation uploads it to an
Amazon Simple Storage Service (Amazon S3) bucket in your AWS account. If you don't already have
an S3 bucket that was created by AWS CloudFormation, it creates a unique bucket for each region
in which you upload a template file. If you already have an S3 bucket that was created by AWS
CloudFormation in your AWS account, AWS CloudFormation adds the template to that bucket.
Incorrect:
"EBS" - Amazon EBS is a recommended storage option when data must be quickly accessible and
requires long-term persistence
"EFS" - EFS is a file storage service where you mount the file system on an Amazon EC2
Linux-based instance which is not an option for CloudFormation
"ECR" - Amazon ECR eliminates the need to operate your own container repositories or worry about
scaling the underlying infrastructure which is not applicable to CloudFormation