which of the following is true?

When thinking of AWS OpsWorks, which of the following is true?

A.
Stacks have many layers, layers have many instances.

B.
Instances have many stacks, stacks have many layers.

C.
Layers have many stacks, stacks have many instances.

D.
Layers have many instances, instances have many stacks.

Explanation:
The stack is the core AWS OpsWorks component. It is basically a container for AWS resources–Amazon EC2 instances,
Amazon RDS database instances, and so on–that have a common purpose and should be logically managed together.
You define the stack’s constituents by adding one or more layers. A layer represents a set of Amazon EC2 instances that
serve a particular purpose, such as serving applications or hosting a database server. An instance represents a single
computing resource, such as an Amazon EC2 instance.
http://docs.aws.amazon.com/opsworks/latest/userguide/welcome.html