What is the scope of an EC2 security group?
A.
Availability Zone
B.
Placement Group
C.
Region
D.
VPC
Explanation:
A security group is tied to a region and can be assigned only to instances in the same region. You can’t enable an instance
to communicate with an instance outside its region using security group rules. Traffic from an instance in another region
is seen as WAN bandwidth.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/resources.html