What is a placement group in Amazon EC2?

What is a placement group in Amazon EC2?
A . It is a group of EC2 instances within a single Availability Zone.
B . It the edge location of your web content.
C . It is the AWS region where you run the EC2 instance of your web content.
D . It is a group used to span multiple Availability Zones.

Answer: A

Explanation:

A placement group is a logical grouping of instances within a single Availability Zone.

Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html