what is a stack?

In regard to AWS CloudFormation, what is a stack?

A.
The set of AWS templates that are created and managed as a template

B.
The set of AWS resources that are created and managed as a template

C.
The set of AWS resources that are created and managed as a single unit

D.
The set of AWS templates that are created and managed as a single unit

Explanation:
A stack is the set of AWS resources that are created and managed as a single unit when AWS CloudFormation initiates
a template.
http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/concept-stack.html