What types of identities do Amazon Cognito identity pools support?

A.
They support both authenticated and unauthenticated identities.

B.
They support only unauthenticated identities.

C.
They support neither authenticated nor unauthenticated identities.

D.
They support only authenticated identities.

Explanation:
Amazon Cognito identity pools support both authenticated and unauthenticated identities.
Authenticated identities belong to users who are authenticated by a public login provider or your
own backend authentication process. Unauthenticated identities typically belong to guest users.
http://docs.aws.amazon.com/cognito/devguide/identity/identity-pools/