Which of the following are characteristics of Amazon VPC subnets? (Choose two.)

A. Each subnet maps to a single Availability Zone

B. A CIDR block mask of /25 is the smallest range supported
C. Instances in a private subnet can communicate with the internet only if they have an Elastic IP.

D. By default, all subnets can route between each other, whether they are private or public

E. V Each subnet spans at least 2 Availability zones to provide a high-availability environment

Explanation:
“Each subnet must reside entirely within one Availability Zone and cannot span zones.”
“Every subnet that you create is automatically associated with the main route table for the VPC.”
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Subnets.html